diff --git a/packages/backend/src/server/api/index.ts b/packages/backend/src/server/api/index.ts
index 1096d995b..e2a0257e6 100644
--- a/packages/backend/src/server/api/index.ts
+++ b/packages/backend/src/server/api/index.ts
@@ -19,19 +19,11 @@ import signupPending from "./private/signup-pending.js";
 import discord from "./service/discord.js";
 import github from "./service/github.js";
 import twitter from "./service/twitter.js";
+import koaBody from "koa-body";
 
 // Init app
 const app = new Koa();
 
-// Init multer instance
-const upload = multer({
-	storage: multer.diskStorage({}),
-	limits: {
-		fileSize: config.maxFileSize || 262144000,
-		files: 1,
-	},
-});
-
 app.use(
 	cors({
 		origin: "*",
@@ -44,7 +36,20 @@ app.use(async (ctx, next) => {
 	await next();
 });
 
-app.use(
+// Init router
+const router = new Router();
+const mastoRouter = new Router();
+
+// Init multer instance
+const upload = multer({
+	storage: multer.diskStorage({}),
+	limits: {
+		fileSize: config.maxFileSize || 262144000,
+		files: 1,
+	},
+});
+
+router.use(
 	bodyParser({
 		// リクエストが multipart/form-data でない限りはJSONだと見なす
 		detectJSON: (ctx) =>
@@ -55,10 +60,9 @@ app.use(
 	}),
 );
 
-// Init router
-const router = new Router();
+mastoRouter.use(koaBody());
 
-apiMastodonCompatible(router);
+apiMastodonCompatible(mastoRouter);
 
 /**
  * Register endpoint handlers
@@ -150,5 +154,6 @@ router.all("(.*)", async (ctx) => {
 
 // Register router
 app.use(router.routes());
+app.use(mastoRouter.routes());
 
 export default app;
diff --git a/packages/backend/src/server/index.ts b/packages/backend/src/server/index.ts
index 6609627fe..a3cdad438 100644
--- a/packages/backend/src/server/index.ts
+++ b/packages/backend/src/server/index.ts
@@ -29,6 +29,7 @@ import fileServer from "./file/index.js";
 import proxyServer from "./proxy/index.js";
 import webServer from "./web/index.js";
 import { initializeStreamingServer } from "./api/streaming.js";
+import koaBody from "koa-body";
 
 export const serverLogger = new Logger("server", "gray", false);
 
@@ -69,6 +70,9 @@ app.use(mount("/proxy", proxyServer));
 
 // Init router
 const router = new Router();
+const mastoRouter = new Router();
+
+mastoRouter.use(koaBody());
 
 // Routing
 router.use(activityPub.routes());
@@ -134,13 +138,13 @@ router.get("/verify-email/:code", async (ctx) => {
 	}
 });
 
-router.get("/oauth/authorize", async (ctx) => {
+mastoRouter.get("/oauth/authorize", async (ctx) => {
 	const client_id = ctx.request.query.client_id;
 	console.log(ctx.request.req);
 	ctx.redirect(Buffer.from(client_id?.toString() || '', 'base64').toString());
 });
 
-router.post("/oauth/token", async (ctx) => {
+mastoRouter.post("/oauth/token", async (ctx) => {
 	const body: any = ctx.request.body;
 	const BASE_URL = `${ctx.request.protocol}://${ctx.request.hostname}`;
 	const generator = (megalodon as any).default;
@@ -167,6 +171,7 @@ router.post("/oauth/token", async (ctx) => {
 
 // Register router
 app.use(router.routes());
+app.use(mastoRouter.routes());
 
 app.use(mount(webServer));