diff --git a/src/api/bot/core.ts b/src/api/bot/core.ts
index 53fb18119e..8324390880 100644
--- a/src/api/bot/core.ts
+++ b/src/api/bot/core.ts
@@ -232,7 +232,7 @@ class SigninContext extends Context {
 			}
 		} else {
 			// Compare password
-			const same = bcrypt.compareSync(query, this.temporaryUser.password);
+			const same = await bcrypt.compare(query, this.temporaryUser.password);
 
 			if (same) {
 				this.bot.signin(this.temporaryUser);
diff --git a/src/api/endpoints/drive/files/create.ts b/src/api/endpoints/drive/files/create.ts
index 43dca7762a..7967c31187 100644
--- a/src/api/endpoints/drive/files/create.ts
+++ b/src/api/endpoints/drive/files/create.ts
@@ -20,6 +20,7 @@ module.exports = (file, params, user) => new Promise(async (res, rej) => {
 		return rej('file is required');
 	}
 
+	// TODO: 非同期にしたい。Promise対応してないんだろうか...
 	const buffer = fs.readFileSync(file.path);
 	fs.unlink(file.path, (err) => { if (err) console.log(err); });
 
diff --git a/src/api/endpoints/i/change_password.ts b/src/api/endpoints/i/change_password.ts
index faceded29d..16f1a2e4ec 100644
--- a/src/api/endpoints/i/change_password.ts
+++ b/src/api/endpoints/i/change_password.ts
@@ -22,15 +22,15 @@ module.exports = async (params, user) => new Promise(async (res, rej) => {
 	if (newPasswordErr) return rej('invalid new_password param');
 
 	// Compare password
-	const same = bcrypt.compareSync(currentPassword, user.password);
+	const same = await bcrypt.compare(currentPassword, user.password);
 
 	if (!same) {
 		return rej('incorrect password');
 	}
 
 	// Generate hash of password
-	const salt = bcrypt.genSaltSync(8);
-	const hash = bcrypt.hashSync(newPassword, salt);
+	const salt = await bcrypt.genSalt(8);
+	const hash = await bcrypt.hash(newPassword, salt);
 
 	await User.update(user._id, {
 		$set: {
diff --git a/src/api/endpoints/i/regenerate_token.ts b/src/api/endpoints/i/regenerate_token.ts
index f96d10ebfc..653468330f 100644
--- a/src/api/endpoints/i/regenerate_token.ts
+++ b/src/api/endpoints/i/regenerate_token.ts
@@ -20,7 +20,7 @@ module.exports = async (params, user) => new Promise(async (res, rej) => {
 	if (passwordErr) return rej('invalid password param');
 
 	// Compare password
-	const same = bcrypt.compareSync(password, user.password);
+	const same = await bcrypt.compare(password, user.password);
 
 	if (!same) {
 		return rej('incorrect password');
diff --git a/src/api/private/signin.ts b/src/api/private/signin.ts
index c7dc243980..0689887925 100644
--- a/src/api/private/signin.ts
+++ b/src/api/private/signin.ts
@@ -40,7 +40,7 @@ export default async (req: express.Request, res: express.Response) => {
 	}
 
 	// Compare password
-	const same = bcrypt.compareSync(password, user.password);
+	const same = await bcrypt.compare(password, user.password);
 
 	if (same) {
 		const expires = 1000 * 60 * 60 * 24 * 365; // One Year
diff --git a/src/api/private/signup.ts b/src/api/private/signup.ts
index bcc17a876d..7a6b9c098e 100644
--- a/src/api/private/signup.ts
+++ b/src/api/private/signup.ts
@@ -54,8 +54,8 @@ export default async (req: express.Request, res: express.Response) => {
 	}
 
 	// Generate hash of password
-	const salt = bcrypt.genSaltSync(8);
-	const hash = bcrypt.hashSync(password, salt);
+	const salt = await bcrypt.genSalt(8);
+	const hash = await bcrypt.hash(password, salt);
 
 	// Generate secret
 	const secret = generateUserToken();
diff --git a/src/file/server.ts b/src/file/server.ts
index 449fa2d740..f6e218dc10 100644
--- a/src/file/server.ts
+++ b/src/file/server.ts
@@ -33,11 +33,13 @@ app.get('/', (req, res) => {
 });
 
 app.get('/default-avatar.jpg', (req, res) => {
+	// TODO: 非同期にしたい。Promise対応してないんだろうか...
 	const file = fs.readFileSync(`${__dirname}/assets/avatar.jpg`);
 	send(file, 'image/jpeg', req, res);
 });
 
 app.get('/app-default.jpg', (req, res) => {
+	// TODO: 非同期にしたい。Promise対応してないんだろうか...
 	const file = fs.readFileSync(`${__dirname}/assets/dummy.png`);
 	send(file, 'image/png', req, res);
 });
@@ -54,6 +56,7 @@ async function raw(data: Buffer, type: string, download: boolean, res: express.R
 
 async function thumbnail(data: Buffer, type: string, resize: number, res: express.Response): Promise<any> {
 	if (!/^image\/.*$/.test(type)) {
+		// TODO: 非同期にしたい。Promise対応してないんだろうか...
 		data = fs.readFileSync(`${__dirname}/assets/not-an-image.png`);
 	}