diff --git a/packages/backend/src/core/ClipService.ts b/packages/backend/src/core/ClipService.ts
index b69ca8362..df3de63e8 100644
--- a/packages/backend/src/core/ClipService.ts
+++ b/packages/backend/src/core/ClipService.ts
@@ -134,6 +134,10 @@ export class ClipService {
 			throw new ClipService.NoSuchClipError();
 		}
 
+		if (await this.clipNotesRepository.existsBy({ clipId, noteId })) {
+			throw new ClipService.AlreadyAddedError();
+		}
+
 		const policies = await this.roleService.getUserPolicies(me.id);
 
 		const currentClipCount = await this.clipsRepository.countBy({
@@ -143,6 +147,13 @@ export class ClipService {
 			throw new ClipService.ClipLimitExceededError();
 		}
 
+		const currentNoteCount = await this.clipNotesRepository.countBy({
+			clipId: clip.id,
+		});
+		if (currentNoteCount >= policies.noteEachClipsLimit) {
+			throw new ClipService.TooManyClipNotesError();
+		}
+
 		const currentNoteCounts = await this.clipNotesRepository
 			.createQueryBuilder('cn')
 			.select('COUNT(*)')
@@ -154,13 +165,6 @@ export class ClipService {
 			throw new ClipService.ClipNotesLimitExceededError();
 		}
 
-		const currentNoteCount = await this.clipNotesRepository.countBy({
-			clipId: clip.id,
-		});
-		if (currentNoteCount >= policies.noteEachClipsLimit) {
-			throw new ClipService.TooManyClipNotesError();
-		}
-
 		try {
 			await this.clipNotesRepository.insert({
 				id: this.idService.gen(),
diff --git a/packages/backend/src/core/UserSuspendService.ts b/packages/backend/src/core/UserSuspendService.ts
index f9cf38684..677db309d 100644
--- a/packages/backend/src/core/UserSuspendService.ts
+++ b/packages/backend/src/core/UserSuspendService.ts
@@ -9,7 +9,16 @@ import { bindThis } from '@/decorators.js';
 import { DI } from '@/di-symbols.js';
 import type Logger from '@/logger.js';
 import type { MiUser } from '@/models/User.js';
-import type { FollowingsRepository, FollowRequestsRepository } from '@/models/_.js';
+import type {
+	AntennasRepository,
+	ClipNotesRepository,
+	ClipsRepository,
+	FollowingsRepository,
+	FollowRequestsRepository,
+	UserListMembershipsRepository,
+	UserListsRepository,
+	WebhooksRepository,
+} from '@/models/_.js';
 import { QueueService } from '@/core/QueueService.js';
 import { GlobalEventService } from '@/core/GlobalEventService.js';
 import { ApRendererService } from '@/core/activitypub/ApRendererService.js';
@@ -30,6 +39,24 @@ export class UserSuspendService {
 		@Inject(DI.followRequestsRepository)
 		private followRequestsRepository: FollowRequestsRepository,
 
+		@Inject(DI.antennasRepository)
+		private antennasRepository: AntennasRepository,
+
+		@Inject(DI.webhooksRepository)
+		private webhooksRepository: WebhooksRepository,
+
+		@Inject(DI.userListsRepository)
+		private userListsRepository: UserListsRepository,
+
+		@Inject(DI.clipsRepository)
+		private clipsRepository: ClipsRepository,
+
+		@Inject(DI.clipNotesRepository)
+		private clipNotesRepository: ClipNotesRepository,
+
+		@Inject(DI.userListMembershipsRepository)
+		private userListMembershipsRepository: UserListMembershipsRepository,
+
 		private queueService: QueueService,
 		private globalEventService: GlobalEventService,
 		private apRendererService: ApRendererService,
@@ -45,10 +72,41 @@ export class UserSuspendService {
 
 		this.globalEventService.publishInternalEvent('userChangeSuspendedState', { id: user.id, isSuspended: true });
 
-		await Promise.all([
+		const promises: Promise<unknown>[] = [];
+
+		let cursor = '';
+		while (true) { // eslint-disable-line @typescript-eslint/no-unnecessary-condition, no-constant-condition
+			const clipNotes = await this.clipNotesRepository.createQueryBuilder('c')
+				.select('c.id')
+				.innerJoin('c.note', 'n')
+				.where('n.userId = :userId', { userId: user.id })
+				.andWhere('c.id > :cursor', { cursor })
+				.orderBy('c.id', 'ASC')
+				.limit(500)
+				.getRawMany<{ id: string }>();
+
+			if (clipNotes.length === 0) break;
+
+			cursor = clipNotes.at(-1)?.id ?? '';
+
+			promises.push(this.clipNotesRepository.createQueryBuilder()
+				.delete()
+				.where('id IN (:...ids)', { ids: clipNotes.map((clipNote) => clipNote.id) })
+				.execute());
+		}
+
+		await Promise.allSettled([
 			this.followRequestsRepository.delete({ followeeId: user.id }),
 			this.followRequestsRepository.delete({ followerId: user.id }),
-		]).catch(() => null);
+
+			this.antennasRepository.delete({ userId: user.id }),
+			this.webhooksRepository.delete({ userId: user.id }),
+			this.userListsRepository.delete({ userId: user.id }),
+			this.clipsRepository.delete({ userId: user.id }),
+
+			...promises,
+			this.userListMembershipsRepository.delete({ userId: user.id }),
+		]);
 
 		if (this.userEntityService.isLocalUser(user)) {
 			// 知り得る全SharedInboxにDelete配信