diff --git a/BE/src/auth/user.repository.ts b/BE/src/auth/user.repository.ts
index 4259adc..1b37c53 100644
--- a/BE/src/auth/user.repository.ts
+++ b/BE/src/auth/user.repository.ts
@@ -26,6 +26,10 @@ export class UserRepository extends Repository<User> {
       const hashedPassword: string = await bcrypt.hash(password, salt);
       const user = this.create({ email, password: hashedPassword });
       await queryRunner.manager.save(user);
+
+      user.nickname = `익명의 투자자${user.id}`;
+      await queryRunner.manager.save(user);
+
       const asset = this.assetRepository.create({ user_id: user.id });
       await queryRunner.manager.save(asset);
 
@@ -52,6 +56,10 @@ export class UserRepository extends Repository<User> {
         password: hashedPassword,
       });
       await this.save(user);
+
+      user.nickname = `익명의 투자자${user.id}`;
+      await queryRunner.manager.save(user);
+
       const asset = this.assetRepository.create({ user_id: user.id });
       await queryRunner.manager.save(asset);
 
diff --git a/BE/src/auth/user.service.ts b/BE/src/auth/user.service.ts
index f974e73..00ecc92 100644
--- a/BE/src/auth/user.service.ts
+++ b/BE/src/auth/user.service.ts
@@ -21,6 +21,10 @@ export class UserService {
       throw new NotFoundException('존재하지 않는 유저입니다.');
     }
 
+    if (newName.replaceAll(/ /g, '').includes('익명의투자자')) {
+      throw new BadRequestException('사용 불가능한 문자가 포함되어 있습니다.');
+    }
+
     const isDuplicated = await this.userRepository.existsBy({
       nickname: newName,
     });