diff --git a/backend/src/main/java/com/edufocus/edufocus/lecture/entity/Lecture.java b/backend/src/main/java/com/edufocus/edufocus/lecture/entity/Lecture.java
index 5ae3972..b72e926 100644
--- a/backend/src/main/java/com/edufocus/edufocus/lecture/entity/Lecture.java
+++ b/backend/src/main/java/com/edufocus/edufocus/lecture/entity/Lecture.java
@@ -1,10 +1,13 @@
 package com.edufocus.edufocus.lecture.entity;
 
+import com.edufocus.edufocus.qna.entity.Qna;
 import jakarta.persistence.*;
 import lombok.Getter;
 import lombok.Setter;
 
+import java.util.ArrayList;
 import java.util.Date;
+import java.util.List;
 
 @Entity
 @Getter
@@ -12,7 +15,8 @@ import java.util.Date;
 public class Lecture {
 
     @Id @GeneratedValue(strategy = GenerationType.IDENTITY)
-    @Column
+
+    @Column(name="lecture_id")
     private Long id;
 
     @Column(name = "teacher_id")
@@ -38,5 +42,8 @@ public class Lecture {
     @Column
     private boolean online;
 
+//
+//    @OneToMany(mappedBy = "lecture")
+//    private List<Qna> qnas = new ArrayList<>();
 
 }
diff --git a/backend/src/main/java/com/edufocus/edufocus/qna/controller/QnaController.java b/backend/src/main/java/com/edufocus/edufocus/qna/controller/QnaController.java
new file mode 100644
index 0000000..fb3356f
--- /dev/null
+++ b/backend/src/main/java/com/edufocus/edufocus/qna/controller/QnaController.java
@@ -0,0 +1,83 @@
+package com.edufocus.edufocus.qna.controller;
+
+import com.edufocus.edufocus.qna.entity.Qna;
+import com.edufocus.edufocus.qna.service.QnaService;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import okhttp3.Response;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.*;
+
+import java.sql.SQLException;
+import java.util.List;
+
+@RestController
+@RequestMapping("/qna")
+@Slf4j
+@RequiredArgsConstructor
+public class QnaController {
+    private final QnaService qnaService;
+
+
+    @PostMapping
+    public ResponseEntity<Qna> createQna(@RequestBody Qna qna) {
+        try{
+            qnaService.createQna(qna);
+            return new ResponseEntity<>(qna, HttpStatus.CREATED);
+
+        }catch (Exception e){
+            throw new RuntimeException(e);
+        }
+    }
+    @PutMapping("/{id}")
+    public ResponseEntity<Qna> updateQna(@PathVariable Long id, @RequestBody Qna qna) {
+
+        try{
+             qnaService.updateQna(id,qna);
+            return new ResponseEntity<>(qna, HttpStatus.ACCEPTED);
+
+        }catch (Exception e)
+        {
+            throw new RuntimeException(e);        }
+    }
+
+    @DeleteMapping("/{id}")
+    public ResponseEntity<Qna> deleteQna(@PathVariable Long id) {
+        try {
+            qnaService.deleteQna(id);
+            return new ResponseEntity<>(HttpStatus.ACCEPTED);
+
+        } catch (SQLException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    @GetMapping("/{id}")
+    public ResponseEntity<Qna> getQna(@PathVariable Long id) {
+        try{
+           Qna findQna= qnaService.getQna(id);
+            return new ResponseEntity<>(findQna, HttpStatus.ACCEPTED);
+
+        } catch (SQLException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    @GetMapping("/all/{id}")
+    public ResponseEntity<List<Qna>> getAllQna(@PathVariable Long id) {
+        try {
+
+            System.out.print("@@@@@@@@@@@@@@@@@@@@@@@>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>");
+            List<Qna> qnaList= qnaService.getAllQnasByLecture(id);
+            for(Qna qna:qnaList)
+            {
+                System.out.print(qna.toString());
+            }
+            return new ResponseEntity<>(qnaList, HttpStatus.ACCEPTED);
+        } catch (SQLException e) {
+            throw new RuntimeException(e);
+
+        }
+    }
+}
diff --git a/backend/src/main/java/com/edufocus/edufocus/qna/entity/Qna.java b/backend/src/main/java/com/edufocus/edufocus/qna/entity/Qna.java
new file mode 100644
index 0000000..ddbc743
--- /dev/null
+++ b/backend/src/main/java/com/edufocus/edufocus/qna/entity/Qna.java
@@ -0,0 +1,58 @@
+package com.edufocus.edufocus.qna.entity;
+
+import com.edufocus.edufocus.lecture.entity.Lecture;
+import com.edufocus.edufocus.user.model.entity.User;
+import jakarta.persistence.*;
+import lombok.Getter;
+import lombok.Setter;
+import org.checkerframework.checker.units.qual.C;
+
+import java.util.Date;
+
+@Entity
+@Getter
+@Setter
+public class Qna {
+
+    // 연관관계 주인
+
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    @Column(name= "qna_id")
+    private Long id;
+
+    // user_id
+    // lecture_id
+
+
+
+    @Column
+    private String title;
+
+    @Column
+    private String content;
+
+
+    @Column(name = "created_at")
+    @Temporal(TemporalType.DATE)
+    private Date createdAt;
+
+    @Column(name = "modified_at")
+    @Temporal(TemporalType.DATE)
+    private Date modifiedAt;
+
+    @Column
+    private String answer;
+
+
+    @ManyToOne
+    @JoinColumn(name= "id")
+    private User user;
+
+    @ManyToOne
+    @JoinColumn(name= "lecture_id")
+    private Lecture lecture;
+
+
+}
diff --git a/backend/src/main/java/com/edufocus/edufocus/qna/repository/QnaRepository.java b/backend/src/main/java/com/edufocus/edufocus/qna/repository/QnaRepository.java
new file mode 100644
index 0000000..beeba54
--- /dev/null
+++ b/backend/src/main/java/com/edufocus/edufocus/qna/repository/QnaRepository.java
@@ -0,0 +1,18 @@
+package com.edufocus.edufocus.qna.repository;
+
+import com.edufocus.edufocus.qna.entity.Qna;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.query.Param;
+import org.springframework.stereotype.Repository;
+
+import java.util.List;
+
+@Repository
+public interface QnaRepository extends JpaRepository<Qna, Long> {
+
+    @Query(value = "SELECT * FROM qna WHERE lecture_id = :lectureId", nativeQuery = true)
+    List<Qna> findLecture(@Param("lectureId") Long lectureId);
+
+
+}
diff --git a/backend/src/main/java/com/edufocus/edufocus/qna/service/QnaService.java b/backend/src/main/java/com/edufocus/edufocus/qna/service/QnaService.java
new file mode 100644
index 0000000..a1b8d94
--- /dev/null
+++ b/backend/src/main/java/com/edufocus/edufocus/qna/service/QnaService.java
@@ -0,0 +1,19 @@
+package com.edufocus.edufocus.qna.service;
+
+import com.edufocus.edufocus.lecture.entity.Lecture;
+import com.edufocus.edufocus.qna.entity.Qna;
+import jakarta.transaction.Transactional;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+
+import java.sql.SQLException;
+import java.util.List;
+@Service
+public interface QnaService {
+
+    void createQna(Qna qna) throws SQLException;
+    void updateQna(Long id,Qna qna) throws SQLException;
+    void deleteQna(Long id) throws SQLException;
+    Qna getQna(Long id) throws SQLException;
+    List<Qna> getAllQnasByLecture(Long lectureId) throws SQLException;
+}
diff --git a/backend/src/main/java/com/edufocus/edufocus/qna/service/QnaServiceImpl.java b/backend/src/main/java/com/edufocus/edufocus/qna/service/QnaServiceImpl.java
new file mode 100644
index 0000000..18a59c1
--- /dev/null
+++ b/backend/src/main/java/com/edufocus/edufocus/qna/service/QnaServiceImpl.java
@@ -0,0 +1,60 @@
+package com.edufocus.edufocus.qna.service;
+
+import com.edufocus.edufocus.qna.entity.Qna;
+import com.edufocus.edufocus.qna.repository.QnaRepository;
+import jakarta.transaction.Transactional;
+import lombok.RequiredArgsConstructor;
+import lombok.Setter;
+import org.springframework.stereotype.Service;
+
+import java.util.Date;
+import java.util.List;
+import java.util.Optional;
+
+@Service
+@Transactional
+@RequiredArgsConstructor
+public class QnaServiceImpl implements QnaService{
+
+    private final QnaRepository qnaRepository;
+
+
+    @Override
+    public void createQna(Qna qna) {
+
+
+        qnaRepository.save(qna);
+
+    }
+
+    @Override
+    public void updateQna(Long id,Qna qna) {
+
+
+        Optional<Qna> findQna = qnaRepository.findById(id);
+
+            qna.setModifiedAt(new Date());
+            qnaRepository.save(qna);
+
+
+    }
+
+    @Override
+    public void deleteQna(Long id) {
+qnaRepository.deleteById(id);
+    }
+
+    @Override
+    public Qna getQna(Long id) {
+        return null;
+    }
+
+    @Override
+    public List<Qna> getAllQnasByLecture(Long lectureId) {
+
+
+        System.out.printf(lectureId+"!!!!!!!!!!!!!!!!!!!!!!");
+        return qnaRepository.findLecture(lectureId);
+
+    }
+}
diff --git a/backend/src/main/java/com/edufocus/edufocus/user/controller/UserController.java b/backend/src/main/java/com/edufocus/edufocus/user/controller/UserController.java
index 19b306d..ee15c64 100644
--- a/backend/src/main/java/com/edufocus/edufocus/user/controller/UserController.java
+++ b/backend/src/main/java/com/edufocus/edufocus/user/controller/UserController.java
@@ -22,7 +22,7 @@ public class UserController {
     @PostMapping("/join")
     public ResponseEntity<String> join(@RequestBody User user) throws Exception {
 
-        System.out.println("!!!");
+
         userService.join(user);
         return ResponseEntity.ok("User registered successfully");
     }
diff --git a/backend/src/main/java/com/edufocus/edufocus/user/model/entity/User.java b/backend/src/main/java/com/edufocus/edufocus/user/model/entity/User.java
index 8914cd3..e8c64a9 100644
--- a/backend/src/main/java/com/edufocus/edufocus/user/model/entity/User.java
+++ b/backend/src/main/java/com/edufocus/edufocus/user/model/entity/User.java
@@ -1,10 +1,15 @@
 package com.edufocus.edufocus.user.model.entity;
 
+import com.edufocus.edufocus.qna.entity.Qna;
 import jakarta.persistence.*;
 import lombok.AllArgsConstructor;
 import lombok.Getter;
 import lombok.NoArgsConstructor;
 import lombok.Setter;
+import org.checkerframework.checker.units.qual.A;
+
+import java.util.ArrayList;
+import java.util.List;
 
 @Entity
 @Getter
@@ -15,14 +20,19 @@ public class User {
 
     @Id
     @GeneratedValue(strategy = GenerationType.IDENTITY) // 자동 증가 설정
+    @Column(name = "id")
     private Long id;
 
-    private String user_id;
+
+    private String userId;
     private String email;
     private String password;
     @Enumerated(EnumType.STRING) // 혹은 EnumType.ORDINAL
     private UserRole role;
 
 
+//
+//    @OneToMany(mappedBy = "user")
+//    private List<Qna> qnas= new ArrayList<>();
 
 }