diff --git a/src/main/java/final_project/momeasy/domain/child/repository/ChildRepository.java b/src/main/java/final_project/momeasy/domain/child/repository/ChildRepository.java
index 969e519f..a01be775 100644
--- a/src/main/java/final_project/momeasy/domain/child/repository/ChildRepository.java
+++ b/src/main/java/final_project/momeasy/domain/child/repository/ChildRepository.java
@@ -27,4 +27,15 @@ SELECT COUNT(c) > 0 FROM Child c
     boolean existsByChildIdAndParentId(@Param("childId") Long childId, @Param("parentId") Long parentId);
 
     Optional<Child> findByHomecam(Homecam homecam);
+
+    @Query("""
+        SELECT c FROM Child c
+        JOIN ParentChild pc ON pc.child.id = c.id
+        WHERE c.id = :childId
+            AND pc.parent.id = :parentId
+            AND c.deletedAt IS NULL
+    """)
+    Optional<Child> findByIdAndParentId(
+            @Param("childId") Long childId,
+            @Param("parentId") Long parentId);
 }
diff --git a/src/main/java/final_project/momeasy/domain/room_condition/service/RoomConditionQueryServiceImpl.java b/src/main/java/final_project/momeasy/domain/room_condition/service/RoomConditionQueryServiceImpl.java
index 1a943a17..fb816362 100644
--- a/src/main/java/final_project/momeasy/domain/room_condition/service/RoomConditionQueryServiceImpl.java
+++ b/src/main/java/final_project/momeasy/domain/room_condition/service/RoomConditionQueryServiceImpl.java
@@ -1,7 +1,5 @@
 package final_project.momeasy.domain.room_condition.service;
 
-import final_project.momeasy.domain.child.exception.ChildErrorCode;
-import final_project.momeasy.domain.child.exception.ChildException;
 import final_project.momeasy.domain.child.repository.ChildRepository;
 import final_project.momeasy.domain.parent.entity.Parent;
 import final_project.momeasy.domain.room_condition.converter.RoomConditionConverter;
@@ -27,27 +25,26 @@ public class RoomConditionQueryServiceImpl implements RoomConditionQueryService
 
     @Override
     public RoomConditionResponseDTO.RoomConditionViewDTO getRoomCondition(Long childId, Parent parent) {
-        childRepository.findById(childId).orElseThrow(() -> new ChildException(ChildErrorCode.NOT_FOUND));
-        if (!childRepository.existsByChildIdAndParentId(childId, parent.getId())) {
-            throw new RoomConditionException(RoomConditionErrorCode.UNAUTHORIZED_ACCESS);
-        }
-        RoomCondition roomCondition = roomConditionRepository.findTopByChildIdOrderByCreatedAtDesc(childId).orElseThrow(() -> new RoomConditionException(RoomConditionErrorCode.NOT_FOUND));
+        validateChildAccess(childId, parent);
+        RoomCondition roomCondition = roomConditionRepository.findTopByChildIdOrderByCreatedAtDesc(childId)
+                .orElseThrow(() ->
+                        new RoomConditionException(RoomConditionErrorCode.NOT_FOUND));
         return RoomConditionConverter.toRoomConditionViewDTO(roomCondition);
     }
 
     @Override
     public RoomConditionResponseDTO.RoomConditionListViewDTO getRoomConditionPage(Long childId, Long cursor, Integer size, Parent parent) {
-        childRepository.findById(childId).orElseThrow(() -> new ChildException(ChildErrorCode.NOT_FOUND));
-        if (!childRepository.existsByChildIdAndParentId(childId, parent.getId())) {
-            throw new RoomConditionException(RoomConditionErrorCode.UNAUTHORIZED_ACCESS);
-        }
+        validateChildAccess(childId, parent);
+
         if (cursor == 0) {
             cursor = Long.MAX_VALUE;
         }
         Pageable pageable = PageRequest.of(0, size);
         Slice<RoomCondition> roomConditionList = roomConditionRepository.findRoomConditionCursorPagination(childId, cursor, pageable);
         List<RoomCondition> roomConditions = roomConditionList.toList();
-        List<RoomConditionResponseDTO.RoomConditionViewDTO> roomConditionViewDTOS = roomConditions.stream().map(RoomConditionConverter::toRoomConditionViewDTO).toList();
+        List<RoomConditionResponseDTO.RoomConditionViewDTO> roomConditionViewDTOS = roomConditions.stream()
+                .map(RoomConditionConverter::toRoomConditionViewDTO)
+                .toList();
         if (roomConditionList.isEmpty()) {
             throw new RoomConditionException(RoomConditionErrorCode.NOT_FOUND);
         }
@@ -57,33 +54,32 @@ public RoomConditionResponseDTO.RoomConditionListViewDTO getRoomConditionPage(Lo
             nextCursor = roomConditions.get(roomConditions.size() - 1).getId();
         }
 
-        return RoomConditionConverter.toRoomConditionListViewDTO(roomConditionViewDTOS, roomConditionList.hasNext(), nextCursor);
+        return RoomConditionConverter
+                .toRoomConditionListViewDTO(roomConditionViewDTOS, roomConditionList.hasNext(), nextCursor);
     }
 
     @Override
     public List<RoomConditionResponseDTO.RoomConditionGrpahDTO> getRoomConditionGraphDay1(Long childId, Parent parent) {
-        childRepository.findById(childId).orElseThrow(() -> new ChildException(ChildErrorCode.NOT_FOUND));
-        if (!childRepository.existsByChildIdAndParentId(childId, parent.getId())) {
-            throw new RoomConditionException(RoomConditionErrorCode.UNAUTHORIZED_ACCESS);
-        }
+        validateChildAccess(childId, parent);
         return roomConditionGraphGenerator.createDay1(childId);
     }
 
     @Override
     public List<RoomConditionResponseDTO.RoomConditionGrpahDTO> getRoomConditionGraphDay3(Long childId, Parent parent) {
-        childRepository.findById(childId).orElseThrow(() -> new ChildException(ChildErrorCode.NOT_FOUND));
-        if (!childRepository.existsByChildIdAndParentId(childId, parent.getId())) {
-            throw new RoomConditionException(RoomConditionErrorCode.UNAUTHORIZED_ACCESS);
-        }
+        validateChildAccess(childId, parent);
         return roomConditionGraphGenerator.createDay3(childId);
     }
 
     @Override
     public List<RoomConditionResponseDTO.RoomConditionGrpahDTO> getRoomConditionGraphDay7(Long childId, Parent parent) {
-        childRepository.findById(childId).orElseThrow(() -> new ChildException(ChildErrorCode.NOT_FOUND));
-        if (!childRepository.existsByChildIdAndParentId(childId, parent.getId())) {
-            throw new RoomConditionException(RoomConditionErrorCode.UNAUTHORIZED_ACCESS);
-        }
+        validateChildAccess(childId, parent);
         return roomConditionGraphGenerator.createDay7(childId);
     }
+
+    private void validateChildAccess(Long childId, Parent parent) {
+        childRepository.findByIdAndParentId(childId, parent.getId())
+                .orElseThrow(() ->
+                        new RoomConditionException(RoomConditionErrorCode.UNAUTHORIZED_ACCESS)
+                );
+    }
 }