diff --git a/packages/backend/src/core/NoteUpdateService.ts b/packages/backend/src/core/NoteUpdateService.ts
index 9a24b8ae5..3f7aecaf3 100644
--- a/packages/backend/src/core/NoteUpdateService.ts
+++ b/packages/backend/src/core/NoteUpdateService.ts
@@ -68,6 +68,15 @@ export class NoteUpdateService {
 	 * @param ps New note info
 	 */
 	async update(user: { id: MiUser['id']; uri: MiUser['uri']; host: MiUser['host']; isBot: MiUser['isBot']; }, note: MiNote, ps: Pick<MiNote, 'text' | 'cw' | 'updatedAt'>, quiet = false, updater?: MiUser) {
+		if (!ps.updatedAt) {
+			throw new Error('update time is required');
+		}
+
+		if (note.history?.findIndex(h => h.createdAt === ps.updatedAt?.toISOString()) !== -1) {
+			// Same history already exists, skip this
+			return;
+		}
+
 		const newNote = {
 			...note,
 			...ps, // Overwrite updated fields
@@ -90,18 +99,33 @@ export class NoteUpdateService {
 			}
 		}
 
-		this.searchService.indexNote(newNote);
+		// Check if is latest or previous version
+		const history = [...(note.history || []), {
+			createdAt: (note.updatedAt || this.idService.parse(note.id).date).toISOString(),
+			cw: note.cw,
+			text: note.text,
+		}];
+		if (note.updatedAt && note.updatedAt >= ps.updatedAt) {
+			// Previous version, just update history
+			history.sort((h1, h2) => new Date(h1.createdAt).getTime() - new Date(h2.createdAt).getTime()); // earliest -> latest
 
-		await this.notesRepository.update({ id: note.id }, {
-			updatedAt: ps.updatedAt,
-			history: [...(note.history || []), {
-				createdAt: (note.updatedAt || this.idService.parse(note.id).date).toISOString(),
-				cw: note.cw,
-				text: note.text,
-			}],
-			cw: ps.cw,
-			text: ps.text,
-		});
+			await this.notesRepository.update({ id: note.id }, {
+				history,
+			});
+		} else {
+			// Latest version
+
+			// Update index
+			this.searchService.indexNote(newNote);
+
+			// Update note info
+			await this.notesRepository.update({ id: note.id }, {
+				updatedAt: ps.updatedAt,
+				history,
+				cw: ps.cw,
+				text: ps.text,
+			});
+		}
 
 		// Currently not implemented
 		// if (updater && (note.userId !== updater.id)) {
diff --git a/packages/backend/src/core/activitypub/models/ApNoteService.ts b/packages/backend/src/core/activitypub/models/ApNoteService.ts
index 0049b866c..e7c6a5c1b 100644
--- a/packages/backend/src/core/activitypub/models/ApNoteService.ts
+++ b/packages/backend/src/core/activitypub/models/ApNoteService.ts
@@ -335,17 +335,22 @@ export class ApNoteService {
 		const uri = typeof value === 'string' ? value : value.id;
 		if (uri == null) throw new Error('uri is null');
 
-		// Is from local
+		// Check if note is from local
 		if (uri.startsWith(`${this.config.url}/`)) throw new Error('uri points local');
 
 		const originNote = await this.notesRepository.findOneBy({ uri });
-		if (originNote == null) throw new Error('Note is not registered');
+		if (originNote === null) throw new Error('note is not registered');
 
 		// Process new note
 		const note = value as IPost;
 
+		// Check updated timestamp
+		if (!note.updated) {
+			throw new Error('note.updated field is required');
+		}
+
 		// Fetch note author
-		if (note.attributedTo == null) {
+		if (!note.attributedTo) {
 			throw new Error('invalid note.attributedTo: ' + note.attributedTo);
 		}
 
@@ -363,12 +368,10 @@ export class ApNoteService {
 			text = this.apMfmService.htmlToMfm(note.content, note.tag);
 		}
 
-		const updatedAt = note.updated || new Date();
-
 		await this.noteUpdateService.update(actor, originNote, {
 			cw,
 			text,
-			updatedAt,
+			updatedAt: note.updated,
 		}, silent);
 	}
 
diff --git a/packages/backend/src/server/api/endpoints/notes/update.ts b/packages/backend/src/server/api/endpoints/notes/update.ts
index 1e6981294..e78fcb6ce 100644
--- a/packages/backend/src/server/api/endpoints/notes/update.ts
+++ b/packages/backend/src/server/api/endpoints/notes/update.ts
@@ -70,6 +70,11 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 				throw new ApiError(meta.errors.noSuchNote);
 			}
 
+			if (note.text === ps.text && note.cw === ps.cw) {
+				// The same as old note, nothing to do
+				return;
+			}
+
 			await this.noteUpdateService.update(await this.usersRepository.findOneByOrFail({ id: note.userId }), note, {
 				text: ps.text,
 				cw: ps.cw,