diff --git a/CHANGELOG.md b/CHANGELOG.md
index 51c008c973..23de5957fd 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -30,6 +30,9 @@
 - Fix: 空文字列のリアクションはフォールバックされるように
 - Fix: リノートにリアクションできないように
 
+### Misskey.js
+- Feat: `/drive/files/create` のリクエストに対応（`multipart/form-data`に対応）
+
 ## 2024.5.0
 
 ### Note
diff --git a/packages/misskey-js/etc/misskey-js.api.md b/packages/misskey-js/etc/misskey-js.api.md
index bea89f2a7c..be2f510ac2 100644
--- a/packages/misskey-js/etc/misskey-js.api.md
+++ b/packages/misskey-js/etc/misskey-js.api.md
@@ -1869,7 +1869,7 @@ type FetchExternalResourcesResponse = operations['fetch-external-resources']['re
 // @public (undocumented)
 type FetchLike = (input: string, init?: {
     method?: string;
-    body?: string;
+    body?: Blob | FormData | string;
     credentials?: RequestCredentials;
     cache?: RequestCache;
     headers: {
diff --git a/packages/misskey-js/generator/src/generator.ts b/packages/misskey-js/generator/src/generator.ts
index 78178d7c7e..4ae00a4522 100644
--- a/packages/misskey-js/generator/src/generator.ts
+++ b/packages/misskey-js/generator/src/generator.ts
@@ -20,7 +20,14 @@ async function generateBaseTypes(
 	}
 	lines.push('');
 
-	const generatedTypes = await openapiTS(openApiJsonPath, { exportType: true });
+	const generatedTypes = await openapiTS(openApiJsonPath, {
+		exportType: true,
+		transform(schemaObject) {
+			if ('format' in schemaObject && schemaObject.format === 'binary') {
+				return schemaObject.nullable ? 'Blob | null' : 'Blob';
+			}
+		},
+	});
 	lines.push(generatedTypes);
 	lines.push('');
 
@@ -56,6 +63,8 @@ async function generateEndpoints(
 	endpointOutputPath: string,
 ) {
 	const endpoints: Endpoint[] = [];
+	const endpointReqMediaTypes: EndpointReqMediaType[] = [];
+	const endpointReqMediaTypesSet = new Set<string>();
 
 	// misskey-jsはPOST固定で送っているので、こちらも決め打ちする。別メソッドに対応することがあればこちらも直す必要あり
 	const paths = openApiDocs.paths ?? {};
@@ -78,13 +87,24 @@ async function generateEndpoints(
 			const supportMediaTypes = Object.keys(reqContent);
 			if (supportMediaTypes.length > 0) {
 				// いまのところ複数のメディアタイプをとるエンドポイントは無いので決め打ちする
-				endpoint.request = new OperationTypeAlias(
+				const req = new OperationTypeAlias(
 					operationId,
 					path,
 					supportMediaTypes[0],
 					OperationsAliasType.REQUEST,
 				);
+				endpoint.request = req;
+
+				const reqType = new EndpointReqMediaType(path, req);
+				endpointReqMediaTypesSet.add(reqType.getMediaType());
+				endpointReqMediaTypes.push(reqType);
+			} else {
+				endpointReqMediaTypesSet.add('application/json');
+				endpointReqMediaTypes.push(new EndpointReqMediaType(path, undefined, 'application/json'));
 			}
+		} else {
+			endpointReqMediaTypesSet.add('application/json');
+			endpointReqMediaTypes.push(new EndpointReqMediaType(path, undefined, 'application/json'));
 		}
 
 		if (operation.responses && isResponseObject(operation.responses['200']) && operation.responses['200'].content) {
@@ -137,6 +157,19 @@ async function generateEndpoints(
 	endpointOutputLine.push('}');
 	endpointOutputLine.push('');
 
+	function generateEndpointReqMediaTypesType() {
+		return `Record<keyof Endpoints, ${[...endpointReqMediaTypesSet].map((t) => `'${t}'`).join(' | ')}>`;
+	}
+
+	endpointOutputLine.push(`export const endpointReqTypes: ${generateEndpointReqMediaTypesType()} = {`);
+
+	endpointOutputLine.push(
+		...endpointReqMediaTypes.map(it => '\t' + it.toLine()),
+	);
+
+	endpointOutputLine.push('};');
+	endpointOutputLine.push('');
+
 	await writeFile(endpointOutputPath, endpointOutputLine.join('\n'));
 }
 
@@ -314,6 +347,26 @@ class Endpoint {
 	}
 }
 
+class EndpointReqMediaType {
+	public readonly path: string;
+	public readonly mediaType: string;
+
+	constructor(path: string, request: OperationTypeAlias, mediaType?: undefined);
+	constructor(path: string, request: undefined, mediaType: string);
+	constructor(path: string, request: OperationTypeAlias | undefined, mediaType?: string) {
+		this.path = path;
+		this.mediaType = mediaType ?? request?.mediaType ?? 'application/json';
+	}
+
+	getMediaType(): string {
+		return this.mediaType;
+	}
+
+	toLine(): string {
+		return `'${this.path}': '${this.mediaType}',`;
+	}
+}
+
 async function main() {
 	const generatePath = './built/autogen';
 	await mkdir(generatePath, { recursive: true });
diff --git a/packages/misskey-js/src/api.ts b/packages/misskey-js/src/api.ts
index 959a634a74..76d055cbe4 100644
--- a/packages/misskey-js/src/api.ts
+++ b/packages/misskey-js/src/api.ts
@@ -1,7 +1,7 @@
 import './autogen/apiClientJSDoc.js';
 
-import { SwitchCaseResponseType } from './api.types.js';
-import type { Endpoints } from './api.types.js';
+import { endpointReqTypes } from './autogen/endpoint.js';
+import type { SwitchCaseResponseType, Endpoints } from './api.types.js';
 
 export type {
 	SwitchCaseResponseType,
@@ -23,7 +23,7 @@ export function isAPIError(reason: Record<PropertyKey, unknown>): reason is APIE
 
 export type FetchLike = (input: string, init?: {
 	method?: string;
-	body?: string;
+	body?: Blob | FormData | string;
 	credentials?: RequestCredentials;
 	cache?: RequestCache;
 	headers: { [key in string]: string }
@@ -49,20 +49,55 @@ export class APIClient {
 		this.fetch = opts.fetch ?? ((...args) => fetch(...args));
 	}
 
+	private assertIsRecord<T>(obj: T): obj is T & Record<string, any> {
+		return obj !== null && typeof obj === 'object' && !Array.isArray(obj);
+	}
+
 	public request<E extends keyof Endpoints, P extends Endpoints[E]['req']>(
 		endpoint: E,
 		params: P = {} as P,
 		credential?: string | null,
 	): Promise<SwitchCaseResponseType<E, P>> {
 		return new Promise((resolve, reject) => {
-			this.fetch(`${this.origin}/api/${endpoint}`, {
-				method: 'POST',
-				body: JSON.stringify({
+			let mediaType = 'application/json';
+			if (endpoint in endpointReqTypes) {
+				mediaType = endpointReqTypes[endpoint];
+			}
+			let payload: FormData | string = '{}';
+
+			if (mediaType === 'application/json') {
+				payload = JSON.stringify({
 					...params,
 					i: credential !== undefined ? credential : this.credential,
-				}),
+				});
+			} else if (mediaType === 'multipart/form-data') {
+				payload = new FormData();
+				const i = credential !== undefined ? credential : this.credential;
+				if (i != null) {
+					payload.append('i', i);
+				}
+				if (this.assertIsRecord(params)) {
+					for (const key in params) {
+						const value = params[key];
+
+						if (value == null) continue;
+
+						if (value instanceof File || value instanceof Blob) {
+							payload.append(key, value);
+						} else if (typeof value === 'object') {
+							payload.append(key, JSON.stringify(value));
+						} else {
+							payload.append(key, value);
+						}
+					}
+				}
+			}
+
+			this.fetch(`${this.origin}/api/${endpoint}`, {
+				method: 'POST',
+				body: payload,
 				headers: {
-					'Content-Type': 'application/json',
+					'Content-Type': endpointReqTypes[endpoint],
 				},
 				credentials: 'omit',
 				cache: 'no-cache',
diff --git a/packages/misskey-js/src/autogen/endpoint.ts b/packages/misskey-js/src/autogen/endpoint.ts
index 20c8509d4c..be41951e4d 100644
--- a/packages/misskey-js/src/autogen/endpoint.ts
+++ b/packages/misskey-js/src/autogen/endpoint.ts
@@ -954,3 +954,385 @@ export type Endpoints = {
 	'reversi/surrender': { req: ReversiSurrenderRequest; res: EmptyResponse };
 	'reversi/verify': { req: ReversiVerifyRequest; res: ReversiVerifyResponse };
 }
+
+export const endpointReqTypes: Record<keyof Endpoints, 'application/json' | 'multipart/form-data'> = {
+	'admin/meta': 'application/json',
+	'admin/abuse-user-reports': 'application/json',
+	'admin/abuse-report/notification-recipient/list': 'application/json',
+	'admin/abuse-report/notification-recipient/show': 'application/json',
+	'admin/abuse-report/notification-recipient/create': 'application/json',
+	'admin/abuse-report/notification-recipient/update': 'application/json',
+	'admin/abuse-report/notification-recipient/delete': 'application/json',
+	'admin/accounts/create': 'application/json',
+	'admin/accounts/delete': 'application/json',
+	'admin/accounts/find-by-email': 'application/json',
+	'admin/ad/create': 'application/json',
+	'admin/ad/delete': 'application/json',
+	'admin/ad/list': 'application/json',
+	'admin/ad/update': 'application/json',
+	'admin/announcements/create': 'application/json',
+	'admin/announcements/delete': 'application/json',
+	'admin/announcements/list': 'application/json',
+	'admin/announcements/update': 'application/json',
+	'admin/avatar-decorations/create': 'application/json',
+	'admin/avatar-decorations/delete': 'application/json',
+	'admin/avatar-decorations/list': 'application/json',
+	'admin/avatar-decorations/update': 'application/json',
+	'admin/delete-all-files-of-a-user': 'application/json',
+	'admin/unset-user-avatar': 'application/json',
+	'admin/unset-user-banner': 'application/json',
+	'admin/drive/clean-remote-files': 'application/json',
+	'admin/drive/cleanup': 'application/json',
+	'admin/drive/files': 'application/json',
+	'admin/drive/show-file': 'application/json',
+	'admin/emoji/add-aliases-bulk': 'application/json',
+	'admin/emoji/add': 'application/json',
+	'admin/emoji/copy': 'application/json',
+	'admin/emoji/delete-bulk': 'application/json',
+	'admin/emoji/delete': 'application/json',
+	'admin/emoji/import-zip': 'application/json',
+	'admin/emoji/list-remote': 'application/json',
+	'admin/emoji/list': 'application/json',
+	'admin/emoji/remove-aliases-bulk': 'application/json',
+	'admin/emoji/set-aliases-bulk': 'application/json',
+	'admin/emoji/set-category-bulk': 'application/json',
+	'admin/emoji/set-license-bulk': 'application/json',
+	'admin/emoji/update': 'application/json',
+	'admin/federation/delete-all-files': 'application/json',
+	'admin/federation/refresh-remote-instance-metadata': 'application/json',
+	'admin/federation/remove-all-following': 'application/json',
+	'admin/federation/update-instance': 'application/json',
+	'admin/get-index-stats': 'application/json',
+	'admin/get-table-stats': 'application/json',
+	'admin/get-user-ips': 'application/json',
+	'admin/invite/create': 'application/json',
+	'admin/invite/list': 'application/json',
+	'admin/promo/create': 'application/json',
+	'admin/queue/clear': 'application/json',
+	'admin/queue/deliver-delayed': 'application/json',
+	'admin/queue/inbox-delayed': 'application/json',
+	'admin/queue/promote': 'application/json',
+	'admin/queue/stats': 'application/json',
+	'admin/relays/add': 'application/json',
+	'admin/relays/list': 'application/json',
+	'admin/relays/remove': 'application/json',
+	'admin/reset-password': 'application/json',
+	'admin/resolve-abuse-user-report': 'application/json',
+	'admin/send-email': 'application/json',
+	'admin/server-info': 'application/json',
+	'admin/show-moderation-logs': 'application/json',
+	'admin/show-user': 'application/json',
+	'admin/show-users': 'application/json',
+	'admin/suspend-user': 'application/json',
+	'admin/unsuspend-user': 'application/json',
+	'admin/update-meta': 'application/json',
+	'admin/delete-account': 'application/json',
+	'admin/update-user-note': 'application/json',
+	'admin/roles/create': 'application/json',
+	'admin/roles/delete': 'application/json',
+	'admin/roles/list': 'application/json',
+	'admin/roles/show': 'application/json',
+	'admin/roles/update': 'application/json',
+	'admin/roles/assign': 'application/json',
+	'admin/roles/unassign': 'application/json',
+	'admin/roles/update-default-policies': 'application/json',
+	'admin/roles/users': 'application/json',
+	'admin/system-webhook/create': 'application/json',
+	'admin/system-webhook/delete': 'application/json',
+	'admin/system-webhook/list': 'application/json',
+	'admin/system-webhook/show': 'application/json',
+	'admin/system-webhook/update': 'application/json',
+	'announcements': 'application/json',
+	'announcements/show': 'application/json',
+	'antennas/create': 'application/json',
+	'antennas/delete': 'application/json',
+	'antennas/list': 'application/json',
+	'antennas/notes': 'application/json',
+	'antennas/show': 'application/json',
+	'antennas/update': 'application/json',
+	'ap/get': 'application/json',
+	'ap/show': 'application/json',
+	'app/create': 'application/json',
+	'app/show': 'application/json',
+	'auth/accept': 'application/json',
+	'auth/session/generate': 'application/json',
+	'auth/session/show': 'application/json',
+	'auth/session/userkey': 'application/json',
+	'blocking/create': 'application/json',
+	'blocking/delete': 'application/json',
+	'blocking/list': 'application/json',
+	'channels/create': 'application/json',
+	'channels/featured': 'application/json',
+	'channels/follow': 'application/json',
+	'channels/followed': 'application/json',
+	'channels/owned': 'application/json',
+	'channels/show': 'application/json',
+	'channels/timeline': 'application/json',
+	'channels/unfollow': 'application/json',
+	'channels/update': 'application/json',
+	'channels/favorite': 'application/json',
+	'channels/unfavorite': 'application/json',
+	'channels/my-favorites': 'application/json',
+	'channels/search': 'application/json',
+	'charts/active-users': 'application/json',
+	'charts/ap-request': 'application/json',
+	'charts/drive': 'application/json',
+	'charts/federation': 'application/json',
+	'charts/instance': 'application/json',
+	'charts/notes': 'application/json',
+	'charts/user/drive': 'application/json',
+	'charts/user/following': 'application/json',
+	'charts/user/notes': 'application/json',
+	'charts/user/pv': 'application/json',
+	'charts/user/reactions': 'application/json',
+	'charts/users': 'application/json',
+	'clips/add-note': 'application/json',
+	'clips/remove-note': 'application/json',
+	'clips/create': 'application/json',
+	'clips/delete': 'application/json',
+	'clips/list': 'application/json',
+	'clips/notes': 'application/json',
+	'clips/show': 'application/json',
+	'clips/update': 'application/json',
+	'clips/favorite': 'application/json',
+	'clips/unfavorite': 'application/json',
+	'clips/my-favorites': 'application/json',
+	'drive': 'application/json',
+	'drive/files': 'application/json',
+	'drive/files/attached-notes': 'application/json',
+	'drive/files/check-existence': 'application/json',
+	'drive/files/create': 'multipart/form-data',
+	'drive/files/delete': 'application/json',
+	'drive/files/find-by-hash': 'application/json',
+	'drive/files/find': 'application/json',
+	'drive/files/show': 'application/json',
+	'drive/files/update': 'application/json',
+	'drive/files/upload-from-url': 'application/json',
+	'drive/folders': 'application/json',
+	'drive/folders/create': 'application/json',
+	'drive/folders/delete': 'application/json',
+	'drive/folders/find': 'application/json',
+	'drive/folders/show': 'application/json',
+	'drive/folders/update': 'application/json',
+	'drive/stream': 'application/json',
+	'email-address/available': 'application/json',
+	'endpoint': 'application/json',
+	'endpoints': 'application/json',
+	'export-custom-emojis': 'application/json',
+	'federation/followers': 'application/json',
+	'federation/following': 'application/json',
+	'federation/instances': 'application/json',
+	'federation/show-instance': 'application/json',
+	'federation/update-remote-user': 'application/json',
+	'federation/users': 'application/json',
+	'federation/stats': 'application/json',
+	'following/create': 'application/json',
+	'following/delete': 'application/json',
+	'following/update': 'application/json',
+	'following/update-all': 'application/json',
+	'following/invalidate': 'application/json',
+	'following/requests/accept': 'application/json',
+	'following/requests/cancel': 'application/json',
+	'following/requests/list': 'application/json',
+	'following/requests/reject': 'application/json',
+	'gallery/featured': 'application/json',
+	'gallery/popular': 'application/json',
+	'gallery/posts': 'application/json',
+	'gallery/posts/create': 'application/json',
+	'gallery/posts/delete': 'application/json',
+	'gallery/posts/like': 'application/json',
+	'gallery/posts/show': 'application/json',
+	'gallery/posts/unlike': 'application/json',
+	'gallery/posts/update': 'application/json',
+	'get-online-users-count': 'application/json',
+	'get-avatar-decorations': 'application/json',
+	'hashtags/list': 'application/json',
+	'hashtags/search': 'application/json',
+	'hashtags/show': 'application/json',
+	'hashtags/trend': 'application/json',
+	'hashtags/users': 'application/json',
+	'i': 'application/json',
+	'i/2fa/done': 'application/json',
+	'i/2fa/key-done': 'application/json',
+	'i/2fa/password-less': 'application/json',
+	'i/2fa/register-key': 'application/json',
+	'i/2fa/register': 'application/json',
+	'i/2fa/update-key': 'application/json',
+	'i/2fa/remove-key': 'application/json',
+	'i/2fa/unregister': 'application/json',
+	'i/apps': 'application/json',
+	'i/authorized-apps': 'application/json',
+	'i/claim-achievement': 'application/json',
+	'i/change-password': 'application/json',
+	'i/delete-account': 'application/json',
+	'i/export-blocking': 'application/json',
+	'i/export-following': 'application/json',
+	'i/export-mute': 'application/json',
+	'i/export-notes': 'application/json',
+	'i/export-clips': 'application/json',
+	'i/export-favorites': 'application/json',
+	'i/export-user-lists': 'application/json',
+	'i/export-antennas': 'application/json',
+	'i/favorites': 'application/json',
+	'i/gallery/likes': 'application/json',
+	'i/gallery/posts': 'application/json',
+	'i/import-blocking': 'application/json',
+	'i/import-following': 'application/json',
+	'i/import-muting': 'application/json',
+	'i/import-user-lists': 'application/json',
+	'i/import-antennas': 'application/json',
+	'i/notifications': 'application/json',
+	'i/notifications-grouped': 'application/json',
+	'i/page-likes': 'application/json',
+	'i/pages': 'application/json',
+	'i/pin': 'application/json',
+	'i/read-all-unread-notes': 'application/json',
+	'i/read-announcement': 'application/json',
+	'i/regenerate-token': 'application/json',
+	'i/registry/get-all': 'application/json',
+	'i/registry/get-detail': 'application/json',
+	'i/registry/get': 'application/json',
+	'i/registry/keys-with-type': 'application/json',
+	'i/registry/keys': 'application/json',
+	'i/registry/remove': 'application/json',
+	'i/registry/scopes-with-domain': 'application/json',
+	'i/registry/set': 'application/json',
+	'i/revoke-token': 'application/json',
+	'i/signin-history': 'application/json',
+	'i/unpin': 'application/json',
+	'i/update-email': 'application/json',
+	'i/update': 'application/json',
+	'i/move': 'application/json',
+	'i/webhooks/create': 'application/json',
+	'i/webhooks/list': 'application/json',
+	'i/webhooks/show': 'application/json',
+	'i/webhooks/update': 'application/json',
+	'i/webhooks/delete': 'application/json',
+	'invite/create': 'application/json',
+	'invite/delete': 'application/json',
+	'invite/list': 'application/json',
+	'invite/limit': 'application/json',
+	'meta': 'application/json',
+	'emojis': 'application/json',
+	'emoji': 'application/json',
+	'miauth/gen-token': 'application/json',
+	'mute/create': 'application/json',
+	'mute/delete': 'application/json',
+	'mute/list': 'application/json',
+	'renote-mute/create': 'application/json',
+	'renote-mute/delete': 'application/json',
+	'renote-mute/list': 'application/json',
+	'my/apps': 'application/json',
+	'notes': 'application/json',
+	'notes/children': 'application/json',
+	'notes/clips': 'application/json',
+	'notes/conversation': 'application/json',
+	'notes/create': 'application/json',
+	'notes/delete': 'application/json',
+	'notes/favorites/create': 'application/json',
+	'notes/favorites/delete': 'application/json',
+	'notes/featured': 'application/json',
+	'notes/global-timeline': 'application/json',
+	'notes/hybrid-timeline': 'application/json',
+	'notes/local-timeline': 'application/json',
+	'notes/mentions': 'application/json',
+	'notes/polls/recommendation': 'application/json',
+	'notes/polls/vote': 'application/json',
+	'notes/reactions': 'application/json',
+	'notes/reactions/create': 'application/json',
+	'notes/reactions/delete': 'application/json',
+	'notes/renotes': 'application/json',
+	'notes/replies': 'application/json',
+	'notes/search-by-tag': 'application/json',
+	'notes/search': 'application/json',
+	'notes/show': 'application/json',
+	'notes/state': 'application/json',
+	'notes/thread-muting/create': 'application/json',
+	'notes/thread-muting/delete': 'application/json',
+	'notes/timeline': 'application/json',
+	'notes/translate': 'application/json',
+	'notes/unrenote': 'application/json',
+	'notes/user-list-timeline': 'application/json',
+	'notifications/create': 'application/json',
+	'notifications/flush': 'application/json',
+	'notifications/mark-all-as-read': 'application/json',
+	'notifications/test-notification': 'application/json',
+	'page-push': 'application/json',
+	'pages/create': 'application/json',
+	'pages/delete': 'application/json',
+	'pages/featured': 'application/json',
+	'pages/like': 'application/json',
+	'pages/show': 'application/json',
+	'pages/unlike': 'application/json',
+	'pages/update': 'application/json',
+	'flash/create': 'application/json',
+	'flash/delete': 'application/json',
+	'flash/featured': 'application/json',
+	'flash/like': 'application/json',
+	'flash/show': 'application/json',
+	'flash/unlike': 'application/json',
+	'flash/update': 'application/json',
+	'flash/my': 'application/json',
+	'flash/my-likes': 'application/json',
+	'ping': 'application/json',
+	'pinned-users': 'application/json',
+	'promo/read': 'application/json',
+	'roles/list': 'application/json',
+	'roles/show': 'application/json',
+	'roles/users': 'application/json',
+	'roles/notes': 'application/json',
+	'request-reset-password': 'application/json',
+	'reset-db': 'application/json',
+	'reset-password': 'application/json',
+	'server-info': 'application/json',
+	'stats': 'application/json',
+	'sw/show-registration': 'application/json',
+	'sw/update-registration': 'application/json',
+	'sw/register': 'application/json',
+	'sw/unregister': 'application/json',
+	'test': 'application/json',
+	'username/available': 'application/json',
+	'users': 'application/json',
+	'users/clips': 'application/json',
+	'users/followers': 'application/json',
+	'users/following': 'application/json',
+	'users/gallery/posts': 'application/json',
+	'users/get-frequently-replied-users': 'application/json',
+	'users/featured-notes': 'application/json',
+	'users/lists/create': 'application/json',
+	'users/lists/delete': 'application/json',
+	'users/lists/list': 'application/json',
+	'users/lists/pull': 'application/json',
+	'users/lists/push': 'application/json',
+	'users/lists/show': 'application/json',
+	'users/lists/favorite': 'application/json',
+	'users/lists/unfavorite': 'application/json',
+	'users/lists/update': 'application/json',
+	'users/lists/create-from-public': 'application/json',
+	'users/lists/update-membership': 'application/json',
+	'users/lists/get-memberships': 'application/json',
+	'users/notes': 'application/json',
+	'users/pages': 'application/json',
+	'users/flashs': 'application/json',
+	'users/reactions': 'application/json',
+	'users/recommendation': 'application/json',
+	'users/relation': 'application/json',
+	'users/report-abuse': 'application/json',
+	'users/search-by-username-and-host': 'application/json',
+	'users/search': 'application/json',
+	'users/show': 'application/json',
+	'users/achievements': 'application/json',
+	'users/update-memo': 'application/json',
+	'fetch-rss': 'application/json',
+	'fetch-external-resources': 'application/json',
+	'retention': 'application/json',
+	'bubble-game/register': 'application/json',
+	'bubble-game/ranking': 'application/json',
+	'reversi/cancel-match': 'application/json',
+	'reversi/games': 'application/json',
+	'reversi/match': 'application/json',
+	'reversi/invitations': 'application/json',
+	'reversi/show-game': 'application/json',
+	'reversi/surrender': 'application/json',
+	'reversi/verify': 'application/json',
+};
diff --git a/packages/misskey-js/src/autogen/types.ts b/packages/misskey-js/src/autogen/types.ts
index b59f8dcbe3..ff731a2fa6 100644
--- a/packages/misskey-js/src/autogen/types.ts
+++ b/packages/misskey-js/src/autogen/types.ts
@@ -13850,7 +13850,7 @@ export type operations = {
            * Format: binary
            * @description The file contents.
            */
-          file: string;
+          file: Blob;
         };
       };
     };
diff --git a/packages/misskey-js/test/api.ts b/packages/misskey-js/test/api.ts
index fa31d23faa..95f1946fa2 100644
--- a/packages/misskey-js/test/api.ts
+++ b/packages/misskey-js/test/api.ts
@@ -5,13 +5,19 @@ enableFetchMocks();
 
 function getFetchCall(call: any[]) {
 	const { body, method } = call[1];
-	if (body != null && typeof body != 'string') {
+	const contentType = call[1].headers['Content-Type'];
+	if (
+		body == null ||
+		(contentType === 'application/json' && typeof body !== 'string') ||
+		(contentType === 'multipart/form-data' && !(body instanceof FormData))
+	) {
 		throw new Error('invalid body');
 	}
 	return {
 		url: call[0],
 		method: method,
-		body: JSON.parse(body as any)
+		contentType: contentType,
+		body: body instanceof FormData ? Object.fromEntries(body.entries()) : JSON.parse(body),
 	};
 }
 
@@ -45,6 +51,7 @@ describe('API', () => {
 		expect(getFetchCall(fetchMock.mock.calls[0])).toEqual({
 			url: 'https://misskey.test/api/i',
 			method: 'POST',
+			contentType: 'application/json',
 			body: { i: 'TOKEN' }
 		});
 	});
@@ -78,10 +85,52 @@ describe('API', () => {
 		expect(getFetchCall(fetchMock.mock.calls[0])).toEqual({
 			url: 'https://misskey.test/api/notes/show',
 			method: 'POST',
+			contentType: 'application/json',
 			body: { i: 'TOKEN', noteId: 'aaaaa' }
 		});
 	});
 
+	test('multipart/form-data', async () => {
+		fetchMock.resetMocks();
+		fetchMock.mockResponse(async (req) => {
+			if (req.method == 'POST' && req.url == 'https://misskey.test/api/drive/files/create') {
+				if (req.headers.get('Content-Type')?.includes('multipart/form-data')) {
+					return JSON.stringify({ id: 'foo' });
+				} else {
+					return { status: 400 };
+				}
+			} else {
+				return { status: 404 };
+			}
+		});
+
+		const cli = new APIClient({
+			origin: 'https://misskey.test',
+			credential: 'TOKEN',
+		});
+
+		const testFile = new File([], 'foo.txt');
+
+		const res = await cli.request('drive/files/create', {
+			file: testFile,
+			name: null, // nullのパラメータは消える
+		});
+
+		expect(res).toEqual({
+			id: 'foo'
+		});
+
+		expect(getFetchCall(fetchMock.mock.calls[0])).toEqual({
+			url: 'https://misskey.test/api/drive/files/create',
+			method: 'POST',
+			contentType: 'multipart/form-data',
+			body: {
+				i: 'TOKEN',
+				file: testFile,
+			}
+		});
+	});
+
 	test('204 No Content で null が返る', async () => {
 		fetchMock.resetMocks();
 		fetchMock.mockResponse(async (req) => {
@@ -104,6 +153,7 @@ describe('API', () => {
 		expect(getFetchCall(fetchMock.mock.calls[0])).toEqual({
 			url: 'https://misskey.test/api/reset-password',
 			method: 'POST',
+			contentType: 'application/json',
 			body: { i: 'TOKEN', token: 'aaa', password: 'aaa' }
 		});
 	});