diff --git a/src/remote/activitypub/act/follow.ts b/src/remote/activitypub/act/follow.ts
index 236886dc60..6a8b5a1bec 100644
--- a/src/remote/activitypub/act/follow.ts
+++ b/src/remote/activitypub/act/follow.ts
@@ -1,25 +1,23 @@
-import parseAcct from '../../../acct/parse';
 import User, { IRemoteUser } from '../../../models/user';
 import config from '../../../config';
 import follow from '../../../services/following/create';
 import { IFollow } from '../type';
 
 export default async (actor: IRemoteUser, activity: IFollow): Promise<void> => {
-	const prefix = config.url + '/@';
 	const id = typeof activity.object == 'string' ? activity.object : activity.object.id;
 
-	if (!id.startsWith(prefix)) {
+	if (!id.startsWith(config.url + '/')) {
 		return null;
 	}
 
-	const { username, host } = parseAcct(id.slice(prefix.length));
-	if (host !== null) {
-		throw new Error();
+	const followee = await User.findOne({ _id: id.split('/').pop() });
+
+	if (followee === null) {
+		throw new Error('followee not found');
 	}
 
-	const followee = await User.findOne({ username, host });
-	if (followee === null) {
-		throw new Error();
+	if (followee.host != null) {
+		throw new Error('フォローしようとしているユーザーはローカルユーザーではありません');
 	}
 
 	await follow(actor, followee, activity);
diff --git a/src/remote/activitypub/act/undo/follow.ts b/src/remote/activitypub/act/undo/follow.ts
index fcf27c9507..a85cb0305d 100644
--- a/src/remote/activitypub/act/undo/follow.ts
+++ b/src/remote/activitypub/act/undo/follow.ts
@@ -1,25 +1,23 @@
-import parseAcct from '../../../../acct/parse';
 import User, { IRemoteUser } from '../../../../models/user';
 import config from '../../../../config';
 import unfollow from '../../../../services/following/delete';
 import { IFollow } from '../../type';
 
 export default async (actor: IRemoteUser, activity: IFollow): Promise<void> => {
-	const prefix = config.url + '/@';
-	const id = typeof activity == 'string' ? activity : activity.id;
+	const id = typeof activity.object == 'string' ? activity.object : activity.object.id;
 
-	if (!id.startsWith(prefix)) {
+	if (!id.startsWith(config.url + '/')) {
 		return null;
 	}
 
-	const { username, host } = parseAcct(id.slice(prefix.length));
-	if (host !== null) {
-		throw new Error();
+	const followee = await User.findOne({ _id: id.split('/').pop() });
+
+	if (followee === null) {
+		throw new Error('followee not found');
 	}
 
-	const followee = await User.findOne({ username, host });
-	if (followee === null) {
-		throw new Error();
+	if (followee.host != null) {
+		throw new Error('フォロー解除しようとしているユーザーはローカルユーザーではありません');
 	}
 
 	await unfollow(actor, followee, activity);
diff --git a/src/remote/activitypub/renderer/follow.ts b/src/remote/activitypub/renderer/follow.ts
index 89993d9458..bf8eeff06b 100644
--- a/src/remote/activitypub/renderer/follow.ts
+++ b/src/remote/activitypub/renderer/follow.ts
@@ -3,6 +3,6 @@ import { IRemoteUser, ILocalUser } from '../../../models/user';
 
 export default (follower: ILocalUser, followee: IRemoteUser) => ({
 	type: 'Follow',
-	actor: `${config.url}/@${follower.username}`,
+	actor: `${config.url}/users/${follower._id}`,
 	object: followee.uri
 });
diff --git a/src/remote/activitypub/renderer/key.ts b/src/remote/activitypub/renderer/key.ts
index 76e2f13bcc..0d5e52557c 100644
--- a/src/remote/activitypub/renderer/key.ts
+++ b/src/remote/activitypub/renderer/key.ts
@@ -3,8 +3,8 @@ import { extractPublic } from '../../../crypto_key';
 import { ILocalUser } from '../../../models/user';
 
 export default (user: ILocalUser) => ({
-	id: `${config.url}/@${user.username}/publickey`,
+	id: `${config.url}/users/${user._id}/publickey`,
 	type: 'Key',
-	owner: `${config.url}/@${user.username}`,
+	owner: `${config.url}/users/${user._id}`,
 	publicKeyPem: extractPublic(user.keypair)
 });
diff --git a/src/remote/activitypub/renderer/like.ts b/src/remote/activitypub/renderer/like.ts
index 744896cc41..061a10ba84 100644
--- a/src/remote/activitypub/renderer/like.ts
+++ b/src/remote/activitypub/renderer/like.ts
@@ -1,10 +1,8 @@
 import config from '../../../config';
 import { ILocalUser } from '../../../models/user';
 
-export default (user: ILocalUser, note) => {
-	return {
-		type: 'Like',
-		actor: `${config.url}/@${user.username}`,
-		object: note.uri ? note.uri : `${config.url}/notes/${note._id}`
-	};
-};
+export default (user: ILocalUser, note) => ({
+	type: 'Like',
+	actor: `${config.url}/users/${user._id}`,
+	object: note.uri ? note.uri : `${config.url}/notes/${note._id}`
+});
diff --git a/src/remote/activitypub/renderer/note.ts b/src/remote/activitypub/renderer/note.ts
index 48799af084..7cc388dc33 100644
--- a/src/remote/activitypub/renderer/note.ts
+++ b/src/remote/activitypub/renderer/note.ts
@@ -34,7 +34,7 @@ export default async (note: INote) => {
 		_id: note.userId
 	});
 
-	const attributedTo = `${config.url}/@${user.username}`;
+	const attributedTo = `${config.url}/users/${user._id}`;
 
 	return {
 		id: `${config.url}/notes/${note._id}`,
diff --git a/src/remote/activitypub/renderer/person.ts b/src/remote/activitypub/renderer/person.ts
index 7ea6f532fb..82e261029c 100644
--- a/src/remote/activitypub/renderer/person.ts
+++ b/src/remote/activitypub/renderer/person.ts
@@ -3,7 +3,7 @@ import renderKey from './key';
 import config from '../../../config';
 
 export default user => {
-	const id = `${config.url}/@${user.username}`;
+	const id = `${config.url}/users/${user._id}`;
 
 	return {
 		type: 'Person',
diff --git a/src/remote/activitypub/resolve-person.ts b/src/remote/activitypub/resolve-person.ts
index 7d7989a01f..0140811f0a 100644
--- a/src/remote/activitypub/resolve-person.ts
+++ b/src/remote/activitypub/resolve-person.ts
@@ -1,6 +1,5 @@
 import { JSDOM } from 'jsdom';
 import { toUnicode } from 'punycode';
-import parseAcct from '../../acct/parse';
 import config from '../../config';
 import User, { validateUsername, isValidName, isValidDescription, IUser } from '../../models/user';
 import webFinger from '../webfinger';
@@ -10,10 +9,9 @@ import { isCollectionOrOrderedCollection, IObject } from './type';
 
 export default async (value: string | IObject, verifier?: string): Promise<IUser> => {
 	const id = typeof value == 'string' ? value : value.id;
-	const localPrefix = config.url + '/@';
 
-	if (id.startsWith(localPrefix)) {
-		return await User.findOne(parseAcct(id.substr(localPrefix.length)));
+	if (id.startsWith(config.url + '/')) {
+		return await User.findOne({ _id: id.split('/').pop() });
 	}
 
 	const resolver = new Resolver();
diff --git a/src/remote/activitypub/resolver.ts b/src/remote/activitypub/resolver.ts
index 1466139c48..7d45783b47 100644
--- a/src/remote/activitypub/resolver.ts
+++ b/src/remote/activitypub/resolver.ts
@@ -50,7 +50,7 @@ export default class Resolver {
 
 		//#region resolve local objects
 		// TODO
-		//if (value.startsWith(`${config.url}/@`)) {
+		//if (value.startsWith(`${config.url}/`)) {
 		//#endregion
 
 		const object = await request({
diff --git a/src/server/activitypub/inbox.ts b/src/server/activitypub/inbox.ts
index 1b6cc0c00a..643d2945bd 100644
--- a/src/server/activitypub/inbox.ts
+++ b/src/server/activitypub/inbox.ts
@@ -5,7 +5,7 @@ import { createHttp } from '../../queue';
 
 const app = express.Router();
 
-app.post('/@:user/inbox', bodyParser.json({
+app.post('/users/:user/inbox', bodyParser.json({
 	type() {
 		return true;
 	}
diff --git a/src/server/activitypub/outbox.ts b/src/server/activitypub/outbox.ts
index 4557871bc5..1c97c17a2e 100644
--- a/src/server/activitypub/outbox.ts
+++ b/src/server/activitypub/outbox.ts
@@ -4,23 +4,25 @@ import renderNote from '../../remote/activitypub/renderer/note';
 import renderOrderedCollection from '../../remote/activitypub/renderer/ordered-collection';
 import config from '../../config';
 import Note from '../../models/note';
-import withUser from './with-user';
+import User from '../../models/user';
 
 const app = express.Router();
 
-app.get('/@:user/outbox', withUser(username => {
-	return `${config.url}/@${username}/inbox`;
-}, async (user, req, res) => {
+app.get('/users/:user/outbox', async (req, res) => {
+	const userId = req.params.user;
+
+	const user = await User.findOne({ _id: userId });
+
 	const notes = await Note.find({ userId: user._id }, {
 		limit: 20,
 		sort: { _id: -1 }
 	});
 
 	const renderedNotes = await Promise.all(notes.map(note => renderNote(note)));
-	const rendered = renderOrderedCollection(`${config.url}/@${user.username}/inbox`, user.notesCount, renderedNotes);
+	const rendered = renderOrderedCollection(`${config.url}/users/${userId}/inbox`, user.notesCount, renderedNotes);
 	rendered['@context'] = context;
 
 	res.json(rendered);
-}));
+});
 
 export default app;
diff --git a/src/server/activitypub/publickey.ts b/src/server/activitypub/publickey.ts
index b48504927a..aa0c4271b8 100644
--- a/src/server/activitypub/publickey.ts
+++ b/src/server/activitypub/publickey.ts
@@ -1,18 +1,19 @@
 import * as express from 'express';
 import context from '../../remote/activitypub/renderer/context';
 import render from '../../remote/activitypub/renderer/key';
-import config from '../../config';
-import withUser from './with-user';
+import User from '../../models/user';
 
 const app = express.Router();
 
-app.get('/@:user/publickey', withUser(username => {
-	return `${config.url}/@${username}/publickey`;
-}, (user, req, res) => {
+app.get('/users/:user/publickey', async (req, res) => {
+	const userId = req.params.user;
+
+	const user = await User.findOne({ _id: userId });
+
 	const rendered = render(user);
 	rendered['@context'] = context;
 
 	res.json(rendered);
-}));
+});
 
 export default app;
diff --git a/src/server/activitypub/user.ts b/src/server/activitypub/user.ts
index f054974510..9e98e92b6a 100644
--- a/src/server/activitypub/user.ts
+++ b/src/server/activitypub/user.ts
@@ -1,26 +1,19 @@
 import * as express from 'express';
-import config from '../../config';
 import context from '../../remote/activitypub/renderer/context';
 import render from '../../remote/activitypub/renderer/person';
-import withUser from './with-user';
+import User from '../../models/user';
+
+const app = express.Router();
+
+app.get('/users/:user', async (req, res) => {
+	const userId = req.params.user;
+
+	const user = await User.findOne({ _id: userId });
 
-const respond = withUser(username => `${config.url}/@${username}`, (user, req, res) => {
 	const rendered = render(user);
 	rendered['@context'] = context;
 
 	res.json(rendered);
 });
 
-const app = express.Router();
-
-app.get('/@:user', (req, res, next) => {
-	const accepted = req.accepts(['html', 'application/activity+json', 'application/ld+json']);
-
-	if ((['application/activity+json', 'application/ld+json'] as any[]).includes(accepted)) {
-		respond(req, res, next);
-	} else {
-		next();
-	}
-});
-
 export default app;
diff --git a/src/server/activitypub/with-user.ts b/src/server/activitypub/with-user.ts
deleted file mode 100644
index bdbbefb429..0000000000
--- a/src/server/activitypub/with-user.ts
+++ /dev/null
@@ -1,23 +0,0 @@
-import parseAcct from '../../acct/parse';
-import User from '../../models/user';
-
-export default (redirect, respond) => async (req, res, next) => {
-	const { username, host } = parseAcct(req.params.user);
-	if (host !== null) {
-		return res.sendStatus(422);
-	}
-
-	const user = await User.findOne({
-		usernameLower: username.toLowerCase(),
-		host: null
-	});
-	if (user === null) {
-		return res.sendStatus(404);
-	}
-
-	if (username !== user.username) {
-		return res.redirect(redirect(user.username));
-	}
-
-	return respond(user, req, res, next);
-};