diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2399ce8a5..8ce0cc6b3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -27,6 +27,7 @@
 - Fix: pgroongaでの検索時にはじめのキーワードのみが検索に使用される問題を修正  
   (Cherry-picked from https://activitypub.software/TransFem-org/Sharkey/-/merge_requests/886)
 - Fix: メールアドレスの形式が正しくなければ以降の処理を行わないように
+- Fix: フォロワーではないユーザーにリノートもしくは返信された場合にノートのDeleteアクティビティが送られていない問題を修正
 
 ## 2025.2.0
 
diff --git a/packages/backend/src/core/NoteDeleteService.ts b/packages/backend/src/core/NoteDeleteService.ts
index 4ecd2592b..e394506a4 100644
--- a/packages/backend/src/core/NoteDeleteService.ts
+++ b/packages/backend/src/core/NoteDeleteService.ts
@@ -3,7 +3,7 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import { Brackets, In } from 'typeorm';
+import { Brackets, In, IsNull, Not } from 'typeorm';
 import { Injectable, Inject } from '@nestjs/common';
 import type { MiUser, MiLocalUser, MiRemoteUser } from '@/models/User.js';
 import type { MiNote, IMentionedRemoteUsers } from '@/models/Note.js';
@@ -189,13 +189,27 @@ export class NoteDeleteService {
 		}) as MiRemoteUser[];
 	}
 
+	@bindThis
+	private async getRenotedOrRepliedRemoteUsers(note: MiNote) {
+		const query = this.notesRepository.createQueryBuilder('note')
+			.leftJoinAndSelect('note.user', 'user')
+			.where(new Brackets(qb => {
+				qb.orWhere('note.renoteId = :renoteId', { renoteId: note.id });
+				qb.orWhere('note.replyId = :replyId', { replyId: note.id });
+			}))
+			.andWhere({ userHost: Not(IsNull()) });
+		const notes = await query.getMany() as (MiNote & { user: MiRemoteUser })[];
+		const remoteUsers = notes.map(({ user }) => user);
+		return remoteUsers;
+	}
+
 	@bindThis
 	private async deliverToConcerned(user: { id: MiLocalUser['id']; host: null; }, note: MiNote, content: any) {
 		this.apDeliverManagerService.deliverToFollowers(user, content);
 		this.relayService.deliverToRelays(user, content);
-		const remoteUsers = await this.getMentionedRemoteUsers(note);
-		for (const remoteUser of remoteUsers) {
-			this.apDeliverManagerService.deliverToUser(user, content, remoteUser);
-		}
+		this.apDeliverManagerService.deliverToUsers(user, content, [
+			...await this.getMentionedRemoteUsers(note),
+			...await this.getRenotedOrRepliedRemoteUsers(note),
+		]);
 	}
 }
diff --git a/packages/backend/src/core/activitypub/ApDeliverManagerService.ts b/packages/backend/src/core/activitypub/ApDeliverManagerService.ts
index 5d07cd8e8..0140ce9fd 100644
--- a/packages/backend/src/core/activitypub/ApDeliverManagerService.ts
+++ b/packages/backend/src/core/activitypub/ApDeliverManagerService.ts
@@ -196,6 +196,25 @@ export class ApDeliverManagerService {
 		await manager.execute();
 	}
 
+	/**
+	 * Deliver activity to users
+	 * @param actor
+	 * @param activity Activity
+	 * @param targets Target users
+	 */
+	@bindThis
+	public async deliverToUsers(actor: { id: MiLocalUser['id']; host: null; }, activity: IActivity, targets: MiRemoteUser[]): Promise<void> {
+		const manager = new DeliverManager(
+			this.userEntityService,
+			this.followingsRepository,
+			this.queueService,
+			actor,
+			activity,
+		);
+		for (const to of targets) manager.addDirectRecipe(to);
+		await manager.execute();
+	}
+
 	@bindThis
 	public createDeliverManager(actor: { id: MiUser['id']; host: null; }, activity: IActivity | null): DeliverManager {
 		return new DeliverManager(
diff --git a/packages/backend/test-federation/test/note.test.ts b/packages/backend/test-federation/test/note.test.ts
index 220c22e19..1584f9587 100644
--- a/packages/backend/test-federation/test/note.test.ts
+++ b/packages/backend/test-federation/test/note.test.ts
@@ -139,29 +139,99 @@ describe('Note', () => {
 	});
 
 	describe('Deletion', () => {
-		describe('Check Delete consistency', () => {
-			let carol: LoginUser;
+		describe('Check Delete is delivered', () => {
+			describe('To followers', () => {
+				let carol: LoginUser;
 
-			beforeAll(async () => {
-				carol = await createAccount('a.test');
+				beforeAll(async () => {
+					carol = await createAccount('a.test');
 
-				await carol.client.request('following/create', { userId: bobInA.id });
-				await sleep();
+					await carol.client.request('following/create', { userId: bobInA.id });
+					await sleep();
+				});
+
+				test('Check', async () => {
+					const note = (await bob.client.request('notes/create', { text: 'I\'m Bob.' })).createdNote;
+					const noteInA = await resolveRemoteNote('b.test', note.id, carol);
+					await bob.client.request('notes/delete', { noteId: note.id });
+					await sleep();
+
+					await rejects(
+						async () => await carol.client.request('notes/show', { noteId: noteInA.id }),
+						(err: any) => {
+							strictEqual(err.code, 'NO_SUCH_NOTE');
+							return true;
+						},
+					);
+				});
+
+				afterAll(async () => {
+					await carol.client.request('following/delete', { userId: bobInA.id });
+					await sleep();
+				});
 			});
 
-			test('Delete is derivered to followers', async () => {
-				const note = (await bob.client.request('notes/create', { text: 'I\'m Bob.' })).createdNote;
-				const noteInA = await resolveRemoteNote('b.test', note.id, carol);
-				await bob.client.request('notes/delete', { noteId: note.id });
-				await sleep();
+			describe('To renoted and not followed user', () => {
+				test('Check', async () => {
+					const note = (await bob.client.request('notes/create', { text: 'I\'m Bob.' })).createdNote;
+					const noteInA = await resolveRemoteNote('b.test', note.id, alice);
+					await alice.client.request('notes/create', { renoteId: noteInA.id });
+					await sleep();
 
-				await rejects(
-					async () => await carol.client.request('notes/show', { noteId: noteInA.id }),
-					(err: any) => {
-						strictEqual(err.code, 'NO_SUCH_NOTE');
-						return true;
-					},
-				);
+					await bob.client.request('notes/delete', { noteId: note.id });
+					await sleep();
+
+					await rejects(
+						async () => await alice.client.request('notes/show', { noteId: noteInA.id }),
+						(err: any) => {
+							strictEqual(err.code, 'NO_SUCH_NOTE');
+							return true;
+						},
+					);
+				});
+			});
+
+			describe('To replied and not followed user', () => {
+				test('Check', async () => {
+					const note = (await bob.client.request('notes/create', { text: 'I\'m Bob.' })).createdNote;
+					const noteInA = await resolveRemoteNote('b.test', note.id, alice);
+					await alice.client.request('notes/create', { text: 'Hello Bob!', replyId: noteInA.id });
+					await sleep();
+
+					await bob.client.request('notes/delete', { noteId: note.id });
+					await sleep();
+
+					await rejects(
+						async () => await alice.client.request('notes/show', { noteId: noteInA.id }),
+						(err: any) => {
+							strictEqual(err.code, 'NO_SUCH_NOTE');
+							return true;
+						},
+					);
+				});
+			});
+
+			/**
+			 * FIXME: not delivered
+			 * @see https://github.com/misskey-dev/misskey/issues/15548
+			 */
+			describe('To only resolved and not followed user', () => {
+				test.failing('Check', async () => {
+					const note = (await bob.client.request('notes/create', { text: 'I\'m Bob.' })).createdNote;
+					const noteInA = await resolveRemoteNote('b.test', note.id, alice);
+					await sleep();
+
+					await bob.client.request('notes/delete', { noteId: note.id });
+					await sleep();
+
+					await rejects(
+						async () => await alice.client.request('notes/show', { noteId: noteInA.id }),
+						(err: any) => {
+							strictEqual(err.code, 'NO_SUCH_NOTE');
+							return true;
+						},
+					);
+				});
 			});
 		});