diff --git a/packages/backend/src/core/CustomEmojiService.ts b/packages/backend/src/core/CustomEmojiService.ts
index cd906a72af..a909204af2 100755
--- a/packages/backend/src/core/CustomEmojiService.ts
+++ b/packages/backend/src/core/CustomEmojiService.ts
@@ -22,6 +22,7 @@ import { ModerationLogService } from '@/core/ModerationLogService.js';
 import type { Config } from '@/config.js';
 import { DriveService } from './DriveService.js';
 
+
 const parseEmojiStrRegexp = /^([-\w]+)(?:@([\w.-]+))?$/;
 
 @Injectable()
@@ -77,6 +78,14 @@ export class CustomEmojiService implements OnApplicationShutdown {
 		localOnly: boolean;
 		roleIdsThatCanBeUsedThisEmojiAsReaction: MiRole['id'][];
 	}, moderator?: MiUser): Promise<MiEmoji> {
+		// システムユーザーとして再アップロード
+		if (!data.driveFile.user?.isRoot) {
+			data.driveFile = await this.driveService.uploadFromUrl({
+				url: data.driveFile.url,
+				user: null,
+				force: true,
+			});
+		}
 		const emoji = await this.emojisRepository.insertOne({
 			id: this.idService.gen(),
 			updatedAt: new Date(),