diff --git a/src/constant/message.ts b/src/constant/message.ts
index 337d905..26a6ff0 100644
--- a/src/constant/message.ts
+++ b/src/constant/message.ts
@@ -1,4 +1,7 @@
 export const Message = {
+  // 401 Unauthorized
+  TOKEN_REQUIRED: 'Token is required',
+
   // 403 Forbidden
   CANNOT_CREATE_GROUP: 'Cannot create group',
   CANNOT_MODIFY_GROUP: 'Cannot modify group',
diff --git a/src/core/auth/AuthGuard.ts b/src/core/auth/AuthGuard.ts
new file mode 100644
index 0000000..e56716b
--- /dev/null
+++ b/src/core/auth/AuthGuard.ts
@@ -0,0 +1,43 @@
+import { Request } from 'express';
+import {
+  CanActivate,
+  ExecutionContext,
+  Inject,
+  Injectable,
+  UnauthorizedException,
+} from '@nestjs/common';
+
+import { ITokenVerifier, TokenVerifier } from '@sight/core/auth/ITokenVerifier';
+
+import { Message } from '@sight/constant/message';
+import { ClsService } from 'nestjs-cls';
+
+@Injectable()
+export class AuthGuard implements CanActivate {
+  constructor(
+    @Inject(TokenVerifier)
+    private readonly tokenVerifier: ITokenVerifier,
+    private readonly clsService: ClsService,
+  ) {}
+
+  canActivate(context: ExecutionContext): boolean {
+    const req: Request = context.switchToHttp().getRequest();
+    const authorizationHeader = req.headers['authorization'];
+
+    if (!authorizationHeader) {
+      throw new UnauthorizedException(Message.TOKEN_REQUIRED);
+    }
+
+    const token = authorizationHeader.split(' ')[1];
+    if (!token) {
+      throw new UnauthorizedException(Message.TOKEN_REQUIRED);
+    }
+
+    const requester = this.tokenVerifier.verify(token);
+    req['requester'] = requester;
+
+    this.clsService.set('requester', requester);
+
+    return true;
+  }
+}
diff --git a/src/core/auth/AuthModule.ts b/src/core/auth/AuthModule.ts
new file mode 100644
index 0000000..c6cfe08
--- /dev/null
+++ b/src/core/auth/AuthModule.ts
@@ -0,0 +1,12 @@
+import { Module } from '@nestjs/common';
+import { APP_GUARD } from '@nestjs/core';
+
+import { AuthGuard } from '@sight/core/auth/AuthGuard';
+
+@Module({
+  providers: [
+    { provide: APP_GUARD, useClass: AuthGuard },
+    // TODO: TokenVerifier 구현 후 추가
+  ],
+})
+export class AuthModule {}
diff --git a/src/core/auth/IRequester.ts b/src/core/auth/IRequester.ts
new file mode 100644
index 0000000..45dec46
--- /dev/null
+++ b/src/core/auth/IRequester.ts
@@ -0,0 +1,6 @@
+import { UserRole } from '@sight/core/auth/UserRole';
+
+export interface IRequester {
+  userId: string;
+  role: UserRole;
+}
diff --git a/src/core/auth/ITokenVerifier.ts b/src/core/auth/ITokenVerifier.ts
new file mode 100644
index 0000000..766e0de
--- /dev/null
+++ b/src/core/auth/ITokenVerifier.ts
@@ -0,0 +1,7 @@
+import { IRequester } from '@sight/core/auth/IRequester';
+
+export const TokenVerifier = Symbol('TokenVerifier');
+
+export interface ITokenVerifier {
+  verify: (token: string) => IRequester;
+}
diff --git a/src/core/auth/Requester.ts b/src/core/auth/Requester.ts
new file mode 100644
index 0000000..42374ed
--- /dev/null
+++ b/src/core/auth/Requester.ts
@@ -0,0 +1,5 @@
+import { createParamDecorator } from '@nestjs/common';
+
+export const Requester = createParamDecorator((data, req) => {
+  return req['requester'];
+});
diff --git a/src/core/auth/UserRole.ts b/src/core/auth/UserRole.ts
new file mode 100644
index 0000000..f1043a1
--- /dev/null
+++ b/src/core/auth/UserRole.ts
@@ -0,0 +1,5 @@
+export const UserRole = {
+  USER: 'USER',
+  ADMIN: 'ADMIN',
+} as const;
+export type UserRole = (typeof UserRole)[keyof typeof UserRole];
diff --git a/src/core/persistence/transaction/TransactionMiddleware.ts b/src/core/persistence/transaction/TransactionMiddleware.ts
deleted file mode 100644
index 8dd19c4..0000000
--- a/src/core/persistence/transaction/TransactionMiddleware.ts
+++ /dev/null
@@ -1,19 +0,0 @@
-import { EntityManager } from '@mikro-orm/core';
-import { Injectable, NestMiddleware } from '@nestjs/common';
-import { NextFunction } from 'express';
-import { ClsService } from 'nestjs-cls';
-
-import { TRANSACTIONAL_ENTITY_MANAGER } from '@sight/core/persistence/transaction/constant';
-
-@Injectable()
-export class TransactionMiddleware implements NestMiddleware {
-  constructor(
-    private readonly cls: ClsService,
-    private readonly em: EntityManager,
-  ) {}
-
-  use(request: Request, response: Response, next: NextFunction) {
-    this.cls.set(TRANSACTIONAL_ENTITY_MANAGER, this.em);
-    next();
-  }
-}
diff --git a/src/core/persistence/transaction/TransactionModule.ts b/src/core/persistence/transaction/TransactionModule.ts
index 7e3e886..0e308c9 100644
--- a/src/core/persistence/transaction/TransactionModule.ts
+++ b/src/core/persistence/transaction/TransactionModule.ts
@@ -1,25 +1,15 @@
-import {
-  MiddlewareConsumer,
-  Module,
-  NestModule,
-  OnModuleInit,
-} from '@nestjs/common';
+import { Module, OnModuleInit } from '@nestjs/common';
 import { DiscoveryModule } from '@nestjs/core';
 
 import { TransactionalApplier } from '@sight/core/persistence/transaction/TransactionalApplier';
-import { TransactionMiddleware } from '@sight/core/persistence/transaction/TransactionMiddleware';
 
 @Module({
   imports: [DiscoveryModule],
   providers: [TransactionalApplier],
 })
-export class TransactionModule implements NestModule, OnModuleInit {
+export class TransactionModule implements OnModuleInit {
   constructor(private readonly transactionalApplier: TransactionalApplier) {}
 
-  configure(consumer: MiddlewareConsumer) {
-    consumer.apply(TransactionMiddleware).forRoutes('*');
-  }
-
   onModuleInit() {
     this.transactionalApplier.bindTransactional();
   }
diff --git a/src/core/persistence/transaction/TransactionalApplier.ts b/src/core/persistence/transaction/TransactionalApplier.ts
index 04b3a18..15f8cbe 100644
--- a/src/core/persistence/transaction/TransactionalApplier.ts
+++ b/src/core/persistence/transaction/TransactionalApplier.ts
@@ -1,5 +1,5 @@
 import { EntityManager } from '@mikro-orm/core';
-import { Injectable, InternalServerErrorException } from '@nestjs/common';
+import { Injectable } from '@nestjs/common';
 import { ICommandHandler, IEventHandler } from '@nestjs/cqrs';
 import { ClsService } from 'nestjs-cls';
 
@@ -36,25 +36,14 @@ export class TransactionalApplier {
 
   private createWrappedFunction(originalFn: AsyncFn, transaction: boolean) {
     const wrapper = async (...args: any[]) => {
-      const entityManager: EntityManager | undefined = this.cls.get(
-        TRANSACTIONAL_ENTITY_MANAGER,
-      );
-      if (!entityManager) {
-        throw new InternalServerErrorException('Entity manager is not exists');
-      }
-
       if (transaction) {
-        return await entityManager.transactional(async (manager) => {
-          return await this.cls.runWith(
-            { [TRANSACTIONAL_ENTITY_MANAGER]: manager },
-            () => originalFn(args),
-          );
+        return await this.em.transactional(async (manager) => {
+          this.cls.set(TRANSACTIONAL_ENTITY_MANAGER, manager);
+          return await originalFn(args);
         });
       } else {
-        return await this.cls.runWith(
-          { [TRANSACTIONAL_ENTITY_MANAGER]: this.em },
-          () => originalFn(args),
-        );
+        this.cls.set(TRANSACTIONAL_ENTITY_MANAGER, this.em);
+        return await originalFn(args);
       }
     };
     Object.setPrototypeOf(wrapper, originalFn);