diff --git a/src/main/java/kr/co/studyhubinu/studyhubserver/apply/domain/ApplyEntity.java b/src/main/java/kr/co/studyhubinu/studyhubserver/apply/domain/ApplyEntity.java
index 822c7879..623366b9 100644
--- a/src/main/java/kr/co/studyhubinu/studyhubserver/apply/domain/ApplyEntity.java
+++ b/src/main/java/kr/co/studyhubinu/studyhubserver/apply/domain/ApplyEntity.java
@@ -42,6 +42,15 @@ public ApplyEntity(Inspection inspection, String introduce, Long study, Long use
         this.userId = userId;
     }
 
+    public static ApplyEntity of(Long userId, Long studyId, String introduce) {
+        return ApplyEntity.builder()
+                .userId(userId)
+                .study(studyId)
+                .introduce(introduce)
+                .inspection(Inspection.STANDBY)
+                .build();
+    }
+
     public void update(Inspection inspection) {
         this.inspection = inspection;
     }
diff --git a/src/main/java/kr/co/studyhubinu/studyhubserver/apply/repository/ApplyRepository.java b/src/main/java/kr/co/studyhubinu/studyhubserver/apply/repository/ApplyRepository.java
index 6f2a53af..93fd817b 100644
--- a/src/main/java/kr/co/studyhubinu/studyhubserver/apply/repository/ApplyRepository.java
+++ b/src/main/java/kr/co/studyhubinu/studyhubserver/apply/repository/ApplyRepository.java
@@ -6,9 +6,10 @@
 import org.springframework.data.jpa.repository.JpaRepository;
 
 import java.util.List;
+import java.util.Optional;
 
 public interface ApplyRepository extends JpaRepository<ApplyEntity, Long>, ApplyRepositoryCustom {
-    ApplyEntity findByUserIdAndStudyId(Long userId, Long studyId);
+    Optional<ApplyEntity> findByUserIdAndStudyId(Long userId, Long studyId);
 
     List<ApplyEntity> findByUserId(Long userId);
 }
diff --git a/src/main/java/kr/co/studyhubinu/studyhubserver/apply/service/ApplyService.java b/src/main/java/kr/co/studyhubinu/studyhubserver/apply/service/ApplyService.java
index ca1e6809..154f3636 100644
--- a/src/main/java/kr/co/studyhubinu/studyhubserver/apply/service/ApplyService.java
+++ b/src/main/java/kr/co/studyhubinu/studyhubserver/apply/service/ApplyService.java
@@ -1,57 +1,46 @@
 package kr.co.studyhubinu.studyhubserver.apply.service;
 
-import kr.co.studyhubinu.studyhubserver.apply.domain.ApplyEntity;
 import kr.co.studyhubinu.studyhubserver.apply.dto.data.ApplyUserData;
 import kr.co.studyhubinu.studyhubserver.apply.dto.request.EnrollApplyRequest;
 import kr.co.studyhubinu.studyhubserver.apply.dto.request.FindApplyRequest;
 import kr.co.studyhubinu.studyhubserver.apply.dto.request.UpdateApplyRequest;
 import kr.co.studyhubinu.studyhubserver.apply.dto.response.FindApplyResponse;
-import kr.co.studyhubinu.studyhubserver.apply.enums.Inspection;
 import kr.co.studyhubinu.studyhubserver.apply.repository.ApplyRepository;
 import kr.co.studyhubinu.studyhubserver.common.dto.Converter;
+import kr.co.studyhubinu.studyhubserver.exception.apply.ApplyNotFoundException;
+import kr.co.studyhubinu.studyhubserver.exception.apply.SameUserRequestException;
 import kr.co.studyhubinu.studyhubserver.exception.user.UserNotFoundException;
 import kr.co.studyhubinu.studyhubserver.study.StudyRepository;
 import kr.co.studyhubinu.studyhubserver.study.domain.StudyEntity;
 import kr.co.studyhubinu.studyhubserver.user.domain.UserEntity;
 import kr.co.studyhubinu.studyhubserver.user.repository.UserRepository;
+import kr.co.studyhubinu.studyhubserver.apply.domain.ApplyEntity;
 import lombok.RequiredArgsConstructor;
 import org.springframework.data.domain.PageRequest;
 import org.springframework.data.domain.Pageable;
 import org.springframework.data.domain.Slice;
 import org.springframework.stereotype.Service;
-import org.springframework.transaction.annotation.Transactional;
 
-@Service
 @RequiredArgsConstructor
-@Transactional(readOnly = true)
+@Service
 public class ApplyService {
 
     private final UserRepository userRepository;
     private final StudyRepository studyRepository;
     private final ApplyRepository applyRepository;
 
-    @Transactional
     public void enroll(Long userId, EnrollApplyRequest request) {
         UserEntity user = userRepository.findById(userId).orElseThrow(UserNotFoundException::new);
         StudyEntity study = studyRepository.findById(request.getStudyId()).orElseThrow();
-        ApplyEntity apply = toApplyEntity(user, study);
+        validateSameRequest(user, study);
 
-        applyRepository.save(apply);
+        applyRepository.save(ApplyEntity.of(user.getId(), study.getId(), request.getIntroduce()));
     }
 
-    private ApplyEntity toApplyEntity(UserEntity user, StudyEntity study) {
-        return ApplyEntity.builder()
-                .userId(user.getId())
-                .study(study.getId())
-                .inspection(Inspection.STANDBY)
-                .build();
-    }
-
-    @Transactional
     public void update(UpdateApplyRequest request) {
         UserEntity user = userRepository.findById(request.getUserId()).orElseThrow(UserNotFoundException::new);
         StudyEntity study = studyRepository.findById(request.getStudyId()).orElseThrow();
-        ApplyEntity applyEntity = applyRepository.findByUserIdAndStudyId(user.getId(), study.getId());
+        ApplyEntity applyEntity = applyRepository.findByUserIdAndStudyId(user.getId(), study.getId()).orElseThrow(ApplyNotFoundException::new);
         applyEntity.update(request.getInspection());
     }
 
@@ -61,4 +50,10 @@ public FindApplyResponse findApply(FindApplyRequest request, final int page, fin
 
         return new FindApplyResponse((long) size, userData);
     }
+
+    private void validateSameRequest(UserEntity user, StudyEntity study) {
+        if(applyRepository.findByUserIdAndStudyId(user.getId(), study.getId()).isPresent()) {
+            throw new SameUserRequestException();
+        }
+    }
 }
diff --git a/src/main/java/kr/co/studyhubinu/studyhubserver/exception/apply/ApplyNotFoundException.java b/src/main/java/kr/co/studyhubinu/studyhubserver/exception/apply/ApplyNotFoundException.java
new file mode 100644
index 00000000..27547246
--- /dev/null
+++ b/src/main/java/kr/co/studyhubinu/studyhubserver/exception/apply/ApplyNotFoundException.java
@@ -0,0 +1,25 @@
+package kr.co.studyhubinu.studyhubserver.exception.apply;
+
+import kr.co.studyhubinu.studyhubserver.exception.StatusType;
+import kr.co.studyhubinu.studyhubserver.exception.common.CustomException;
+
+public class ApplyNotFoundException extends CustomException {
+
+    private final StatusType status;
+    private static final String message = "조회되는 요청이 없습니다.";
+
+    public ApplyNotFoundException() {
+        super(message);
+        this.status = StatusType.BAD_REQUEST;
+    }
+
+    @Override
+    public StatusType getStatus() {
+        return status;
+    }
+
+    @Override
+    public String getMessage() {
+        return message;
+    }
+}
diff --git a/src/main/java/kr/co/studyhubinu/studyhubserver/exception/apply/SameUserRequestException.java b/src/main/java/kr/co/studyhubinu/studyhubserver/exception/apply/SameUserRequestException.java
new file mode 100644
index 00000000..dda2ed83
--- /dev/null
+++ b/src/main/java/kr/co/studyhubinu/studyhubserver/exception/apply/SameUserRequestException.java
@@ -0,0 +1,25 @@
+package kr.co.studyhubinu.studyhubserver.exception.apply;
+
+import kr.co.studyhubinu.studyhubserver.exception.StatusType;
+import kr.co.studyhubinu.studyhubserver.exception.common.CustomException;
+
+public class SameUserRequestException extends CustomException {
+
+    private final StatusType status;
+    private static final String message = "동일한 유저가 요청한 기록이 있습니다.";
+
+    public SameUserRequestException() {
+        super(message);
+        this.status = StatusType.BAD_REQUEST;
+    }
+
+    @Override
+    public StatusType getStatus() {
+        return status;
+    }
+
+    @Override
+    public String getMessage() {
+        return message;
+    }
+}
diff --git a/src/test/java/kr/co/studyhubinu/studyhubserver/apply/repository/ApplyRepositoryTest.java b/src/test/java/kr/co/studyhubinu/studyhubserver/apply/repository/ApplyRepositoryTest.java
index 6fc4541d..b0b38a9c 100644
--- a/src/test/java/kr/co/studyhubinu/studyhubserver/apply/repository/ApplyRepositoryTest.java
+++ b/src/test/java/kr/co/studyhubinu/studyhubserver/apply/repository/ApplyRepositoryTest.java
@@ -4,6 +4,7 @@
 import kr.co.studyhubinu.studyhubserver.apply.dto.data.ApplyUserData;
 import kr.co.studyhubinu.studyhubserver.apply.dto.request.UpdateApplyRequest;
 import kr.co.studyhubinu.studyhubserver.apply.enums.Inspection;
+import kr.co.studyhubinu.studyhubserver.exception.apply.ApplyNotFoundException;
 import kr.co.studyhubinu.studyhubserver.study.StudyRepository;
 import kr.co.studyhubinu.studyhubserver.study.domain.StudyEntity;
 import kr.co.studyhubinu.studyhubserver.support.fixture.StudyEntityFixture;
@@ -21,6 +22,7 @@
 import javax.persistence.EntityManager;
 import javax.persistence.PersistenceContext;
 import java.util.List;
+import java.util.Optional;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.junit.jupiter.api.Assertions.assertAll;
@@ -83,13 +85,13 @@ class ApplyRepositoryTest {
         applyRepository.save(applyEntity);
         applyRepository.flush();
 
-        ApplyEntity apply = applyRepository.findByUserIdAndStudyId(user.getId(), study.getId());
-        apply.update(updateApplyRequest.getInspection());
+        Optional<ApplyEntity> apply = applyRepository.findByUserIdAndStudyId(user.getId(), study.getId());
+        apply.get().update(updateApplyRequest.getInspection());
         applyRepository.flush();
-        ApplyEntity result = applyRepository.findByUserIdAndStudyId(user.getId(), study.getId());
+        Optional<ApplyEntity> result = applyRepository.findByUserIdAndStudyId(user.getId(), study.getId());
 
         // then
-        assertThat(result.getInspection()).isEqualTo(Inspection.STANDBY);
+        assertThat(result.get().getInspection()).isEqualTo(Inspection.STANDBY);
     }
 
     @Test
@@ -109,7 +111,7 @@ class ApplyRepositoryTest {
         userRepository.flush();
 
         // when
-        ApplyEntity result = applyRepository.findByUserIdAndStudyId(user.getId(), study.getId());
+        ApplyEntity result = applyRepository.findByUserIdAndStudyId(user.getId(), study.getId()).orElseThrow(ApplyNotFoundException::new);
 
         // then
         assertAll(
diff --git a/src/test/java/kr/co/studyhubinu/studyhubserver/apply/service/ApplyServiceTest.java b/src/test/java/kr/co/studyhubinu/studyhubserver/apply/service/ApplyServiceTest.java
index 525738bf..a608cf38 100644
--- a/src/test/java/kr/co/studyhubinu/studyhubserver/apply/service/ApplyServiceTest.java
+++ b/src/test/java/kr/co/studyhubinu/studyhubserver/apply/service/ApplyServiceTest.java
@@ -9,6 +9,8 @@
 import kr.co.studyhubinu.studyhubserver.apply.dto.response.FindApplyResponse;
 import kr.co.studyhubinu.studyhubserver.apply.enums.Inspection;
 import kr.co.studyhubinu.studyhubserver.apply.repository.ApplyRepository;
+import kr.co.studyhubinu.studyhubserver.exception.apply.SameUserRequestException;
+import kr.co.studyhubinu.studyhubserver.exception.user.UserNotFoundException;
 import kr.co.studyhubinu.studyhubserver.study.StudyRepository;
 import kr.co.studyhubinu.studyhubserver.study.domain.StudyEntity;
 import kr.co.studyhubinu.studyhubserver.user.domain.UserEntity;
@@ -26,6 +28,7 @@
 import java.util.List;
 import java.util.Optional;
 
+import static org.junit.Assert.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertAll;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.mockito.ArgumentMatchers.any;
@@ -53,18 +56,18 @@ class ApplyServiceTest {
         EnrollApplyRequest request = EnrollApplyRequest.builder()
                 .studyId(1L)
                 .build();
-        Optional<UserEntity> user = Optional.ofNullable(UserEntity.builder().id(1L).build());
-        Optional<StudyEntity> study = Optional.ofNullable(StudyEntity.builder().id(1L).build());
+        UserEntity user = UserEntity.builder().id(1L).build();
+        StudyEntity study = StudyEntity.builder().id(1L).build();
 
-        when(userRepository.findById(anyLong())).thenReturn(user);
-        when(studyRepository.findById(anyLong())).thenReturn(study);
+        when(userRepository.findById(anyLong())).thenReturn(Optional.ofNullable(user));
+        when(studyRepository.findById(anyLong())).thenReturn(Optional.ofNullable(study));
         when(applyRepository.save(any())).thenReturn(ApplyEntity.builder()
-                .userId(user.get().getId())
-                .study(study.get().getId())
+                .userId(user.getId())
+                .study(study.getId())
                 .build());
 
         // when, then
-        applyService.enroll(user.get().getId(), request);
+        applyService.enroll(user.getId(), request);
     }
 
     @Test
@@ -80,7 +83,7 @@ class ApplyServiceTest {
         Optional<StudyEntity> study = Optional.ofNullable(StudyEntity.builder().id(1L).build());
         when(userRepository.findById(anyLong())).thenReturn(user);
         when(studyRepository.findById(anyLong())).thenReturn(study);
-        when(applyRepository.findByUserIdAndStudyId(1L, 1L)).thenReturn(ApplyEntity.builder().build());
+        when(applyRepository.findByUserIdAndStudyId(1L, 1L)).thenReturn(Optional.ofNullable(ApplyEntity.builder().build()));
 
         // when, then
         applyService.update(request);