diff --git a/packages/backend/src/server/api/endpoints/admin/emoji/adds.ts b/packages/backend/src/server/api/endpoints/admin/emoji/adds.ts
index 90c39c5001..4140f63e54 100644
--- a/packages/backend/src/server/api/endpoints/admin/emoji/adds.ts
+++ b/packages/backend/src/server/api/endpoints/admin/emoji/adds.ts
@@ -8,7 +8,6 @@ import { Endpoint } from '@/server/api/endpoint-base.js';
 import type { DriveFilesRepository } from '@/models/_.js';
 import { DI } from '@/di-symbols.js';
 import { CustomEmojiService } from '@/core/CustomEmojiService.js';
-import { ModerationLogService } from '@/core/ModerationLogService.js';
 import { EmojiEntityService } from '@/core/entities/EmojiEntityService.js';
 import { secureRndstr } from '@/misc/secure-rndstr.js';
 import { ApiError } from '../../../error.js';
@@ -25,6 +24,11 @@ export const meta = {
 			code: 'NO_SUCH_FILE',
 			id: 'fc46b5a4-6b92-4c33-ac66-b806659bb5cf',
 		},
+		duplicateName: {
+			message: 'Duplicate name.',
+			code: 'DUPLICATE_NAME',
+			id: 'f7a3462c-4e6e-4069-8421-b9bd4f4c3975',
+		},
 	},
 } as const;
 
@@ -62,7 +66,6 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 		private customEmojiService: CustomEmojiService,
 
 		private emojiEntityService: EmojiEntityService,
-		private moderationLogService: ModerationLogService,
 	) {
 		super(meta, paramDef, async (ps, me) => {
 			const driveFile = await this.driveFilesRepository.findOneBy({ id: ps.fileId });
@@ -70,6 +73,9 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 
 			const name = driveFile.name.split('.')[0].match(/^[a-z0-9_]+$/) ? driveFile.name.split('.')[0] : `_${secureRndstr(8)}_`;
 
+			const isDuplicate = await this.customEmojiService.checkDuplicate(name);
+			if (isDuplicate) throw new ApiError(meta.errors.duplicateName);
+
 			const emoji = await this.customEmojiService.add({
 				driveFile,
 				name,
@@ -80,7 +86,7 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 				isSensitive: ps.isSensitive ?? false,
 				localOnly: ps.localOnly ?? false,
 				roleIdsThatCanBeUsedThisEmojiAsReaction: ps.roleIdsThatCanBeUsedThisEmojiAsReaction ?? [],
-			});
+			}, me);
 
 			return this.emojiEntityService.packDetailed(emoji);
 		});