diff --git a/backend/src/main/java/com/edufocus/edufocus/board/entity/vo/Board.java b/backend/src/main/java/com/edufocus/edufocus/board/entity/vo/Board.java
index f7ee473..2cca933 100644
--- a/backend/src/main/java/com/edufocus/edufocus/board/entity/vo/Board.java
+++ b/backend/src/main/java/com/edufocus/edufocus/board/entity/vo/Board.java
@@ -9,6 +9,8 @@ import com.fasterxml.jackson.annotation.JsonAutoDetect;
 import jakarta.persistence.*;
 import lombok.*;
 import org.hibernate.annotations.CreationTimestamp;
+import org.hibernate.annotations.OnDelete;
+import org.hibernate.annotations.OnDeleteAction;
 import org.hibernate.annotations.UpdateTimestamp;
 import org.springframework.data.annotation.CreatedDate;
 import org.springframework.data.annotation.LastModifiedDate;
@@ -59,9 +61,9 @@ public class Board {
 
     @ManyToOne(fetch = FetchType.LAZY)
     @JoinColumn(name = "lecture_id")
+    @OnDelete(action = OnDeleteAction.CASCADE)
     private Lecture lecture;
 
-
     @OneToMany(mappedBy = "board", cascade = CascadeType.ALL)
     private List<Comment> comments;
 
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
index af797ee..6216f88 100644
--- a/backend/src/main/java/com/edufocus/edufocus/qna/entity/Qna.java
+++ b/backend/src/main/java/com/edufocus/edufocus/qna/entity/Qna.java
@@ -4,6 +4,8 @@ import com.edufocus.edufocus.lecture.entity.Lecture;
 import com.edufocus.edufocus.user.model.entity.vo.User;
 import jakarta.persistence.*;
 import lombok.*;
+import org.hibernate.annotations.OnDelete;
+import org.hibernate.annotations.OnDeleteAction;
 
 import java.util.Date;
 
@@ -13,6 +15,8 @@ import java.util.Date;
 @Builder
 @NoArgsConstructor
 @AllArgsConstructor
+
+
 public class Qna {
 
     // 연관관계 주인
@@ -50,6 +54,7 @@ public class Qna {
 
     @ManyToOne
     @JoinColumn(name = "lecture_id")
+    @OnDelete(action = OnDeleteAction.CASCADE)
     private Lecture lecture;
 
     private boolean isMine;
diff --git a/backend/src/main/java/com/edufocus/edufocus/report/entity/vo/Report.java b/backend/src/main/java/com/edufocus/edufocus/report/entity/vo/Report.java
index df47ac2..6e5d89a 100644
--- a/backend/src/main/java/com/edufocus/edufocus/report/entity/vo/Report.java
+++ b/backend/src/main/java/com/edufocus/edufocus/report/entity/vo/Report.java
@@ -7,6 +7,8 @@ import com.fasterxml.jackson.annotation.JsonAutoDetect;
 import jakarta.persistence.*;
 import lombok.*;
 import org.hibernate.annotations.CreationTimestamp;
+import org.hibernate.annotations.OnDelete;
+import org.hibernate.annotations.OnDeleteAction;
 import org.springframework.data.annotation.CreatedDate;
 import org.springframework.data.jpa.domain.support.AuditingEntityListener;
 
@@ -50,10 +52,10 @@ public class Report {
     @JoinColumn(name = "reportset_id")
     private ReportSet reportSet;
 
-    @OneToMany(mappedBy = "report",  cascade = CascadeType.REMOVE)
+    @OneToMany(mappedBy = "report", cascade = CascadeType.REMOVE)
     private List<Answer> answers;
 
-    public ReportResponse makeReportResponse(){
+    public ReportResponse makeReportResponse() {
         return ReportResponse.builder()
                 .reportId(id)
                 .name(user.getName())
diff --git a/backend/src/main/java/com/edufocus/edufocus/report/entity/vo/ReportSet.java b/backend/src/main/java/com/edufocus/edufocus/report/entity/vo/ReportSet.java
index fb293ec..c23547c 100644
--- a/backend/src/main/java/com/edufocus/edufocus/report/entity/vo/ReportSet.java
+++ b/backend/src/main/java/com/edufocus/edufocus/report/entity/vo/ReportSet.java
@@ -5,10 +5,9 @@ import com.edufocus.edufocus.quiz.entity.QuizSet;
 import com.edufocus.edufocus.report.entity.dto.ReportSetResponse;
 import com.fasterxml.jackson.annotation.JsonAutoDetect;
 import jakarta.persistence.*;
+import jakarta.persistence.CascadeType;
 import lombok.*;
-import org.hibernate.annotations.ColumnDefault;
-import org.hibernate.annotations.CreationTimestamp;
-import org.hibernate.annotations.GenericGenerator;
+import org.hibernate.annotations.*;
 import org.springframework.data.annotation.CreatedDate;
 import org.springframework.data.jpa.domain.support.AuditingEntityListener;
 
@@ -19,7 +18,6 @@ import java.util.List;
 import java.util.UUID;
 
 
-
 @Entity
 @Getter
 @Builder
@@ -46,6 +44,7 @@ public class ReportSet {
 
     @ManyToOne
     @JoinColumn(name = "lecture_id")
+    @OnDelete(action = OnDeleteAction.CASCADE)
     private Lecture lecture;
 
     @ManyToOne
@@ -60,7 +59,7 @@ public class ReportSet {
                 .build();
     }
 
-    public long findUserId(){
+    public long findUserId() {
         return lecture.getUser().getId();
     }
 }
diff --git a/backend/src/main/java/com/edufocus/edufocus/report/service/ReportServiceImpl.java b/backend/src/main/java/com/edufocus/edufocus/report/service/ReportServiceImpl.java
index 8ebcaaa..6f27dd6 100644
--- a/backend/src/main/java/com/edufocus/edufocus/report/service/ReportServiceImpl.java
+++ b/backend/src/main/java/com/edufocus/edufocus/report/service/ReportServiceImpl.java
@@ -56,7 +56,7 @@ public class ReportServiceImpl implements ReportService {
             String inputAnswer = answerInputList.get(idx);
             boolean isCorrect;
             Answer answer;
-            if (quiz.getAnswer().equals(inputAnswer)) {
+            if (quiz.getAnswer().equalsIgnoreCase(inputAnswer)) {
                 correctCount++;
                 isCorrect = true;
             } else {