diff --git a/packages/backend/src/remote/activitypub/kernel/undo/announce.ts b/packages/backend/src/remote/activitypub/kernel/undo/announce.ts
index a6e9c88c61..32c66cfb7b 100644
--- a/packages/backend/src/remote/activitypub/kernel/undo/announce.ts
+++ b/packages/backend/src/remote/activitypub/kernel/undo/announce.ts
@@ -3,6 +3,13 @@ import type { CacheableRemoteUser } from "@/models/entities/user.js";
 import type { IAnnounce } from "../../type.js";
 import { getApId } from "../../type.js";
 import deleteNote from "@/services/note/delete.js";
+import {
+	type ScyllaNote,
+	scyllaClient,
+	prepared,
+	parseScyllaNote,
+} from "@/db/scylla.js";
+import type { Note } from "@/models/entities/note.js";
 
 export const undoAnnounce = async (
 	actor: CacheableRemoteUser,
@@ -10,10 +17,26 @@ export const undoAnnounce = async (
 ): Promise<string> => {
 	const uri = getApId(activity);
 
-	const note = await Notes.findOneBy({
-		uri,
-		userId: actor.id,
-	});
+	let note: Note | ScyllaNote | null = null;
+
+	if (scyllaClient) {
+		const result = await scyllaClient.execute(
+			prepared.note.select.byUri,
+			[uri],
+			{ prepare: true },
+		);
+		if (result.rowLength > 0) {
+			const candidate = parseScyllaNote(result.first());
+			if (candidate.userId === actor.id) {
+				note = candidate;
+			}
+		}
+	} else {
+		note = await Notes.findOneBy({
+			uri,
+			userId: actor.id,
+		});
+	}
 
 	if (!note) return "skip: no such Announce";