diff --git a/src/main/java/org/cotato/csquiz/domain/generation/service/SessionService.java b/src/main/java/org/cotato/csquiz/domain/generation/service/SessionService.java
index c029158b..8fc3d2e9 100644
--- a/src/main/java/org/cotato/csquiz/domain/generation/service/SessionService.java
+++ b/src/main/java/org/cotato/csquiz/domain/generation/service/SessionService.java
@@ -174,7 +174,7 @@ public void updateSessionImageOrder(UpdateSessionImageOrderRequest request) {
             throw new AppException(ErrorCode.SESSION_IMAGE_COUNT_MISMATCH);
         }
 
-        if (isValidOrderRange(orderList)) {
+        if (!isValidOrderRange(orderList)) {
             throw new AppException(ErrorCode.SESSION_ORDER_INVALID);
         }