diff --git a/packages/backend/src/services/note/delete.ts b/packages/backend/src/services/note/delete.ts
index cf23656f8..356dc3972 100644
--- a/packages/backend/src/services/note/delete.ts
+++ b/packages/backend/src/services/note/delete.ts
@@ -29,6 +29,10 @@ export default async function(user: User, note: Note, quiet = false) {
 		Notes.decrement({ id: note.renoteId }, 'score', 1);
 	}
 
+	if (note.replyId) {
+		await Notes.decrement({ id: note.replyId }, 'repliesCount', 1);
+	}
+
 	if (!quiet) {
 		publishNoteStream(note.id, 'deleted', {
 			deletedAt: deletedAt,
diff --git a/packages/backend/test/note.ts b/packages/backend/test/note.ts
index 62cea5208..942b2709d 100644
--- a/packages/backend/test/note.ts
+++ b/packages/backend/test/note.ts
@@ -333,4 +333,36 @@ describe('Note', () => {
 			assert.strictEqual(res.status, 400);
 		}));
 	});
+
+	describe('notes/delete', () => {
+		it('delete a reply', async(async () => {
+			const mainNoteRes = await request('/notes/create', {
+				text: 'main post',
+			}, alice);
+			const replyOneRes = await request('/notes/create', {
+				text: 'reply one',
+				replyId: mainNoteRes.body.createdNote.id
+			}, alice);
+			const replyTwoRes = await request('/notes/create', {
+				text: 'reply two',
+				replyId: mainNoteRes.body.createdNote.id
+			}, alice);
+
+			const deleteOneRes = await request('/notes/delete', {
+				noteId: replyOneRes.body.createdNote.id,
+			}, alice);
+
+			assert.strictEqual(deleteOneRes.status, 204);
+			let mainNote = await Notes.findOne({id: mainNoteRes.body.createdNote.id});
+			assert.strictEqual(mainNote.repliesCount, 1);
+
+			const deleteTwoRes = await request('/notes/delete', {
+				noteId: replyTwoRes.body.createdNote.id,
+			}, alice);
+
+			assert.strictEqual(deleteTwoRes.status, 204);
+			mainNote = await Notes.findOne({id: mainNoteRes.body.createdNote.id});
+			assert.strictEqual(mainNote.repliesCount, 0);
+		}));
+	});
 });