diff --git a/examples/bbox_detection/labelme2voc.py b/examples/bbox_detection/labelme2voc.py
index 0eca36933..9688fd131 100755
--- a/examples/bbox_detection/labelme2voc.py
+++ b/examples/bbox_detection/labelme2voc.py
@@ -27,7 +27,7 @@ def main():
     )
     parser.add_argument('input_dir', help='input annotated directory')
     parser.add_argument('output_dir', help='output dataset directory')
-    parser.add_argument('--labels', help='labels file')
+    parser.add_argument('--labels', help='labels file', required=True)
     args = parser.parse_args()
 
     if osp.exists(args.output_dir):
diff --git a/examples/instance_segmentation/labelme2coco.py b/examples/instance_segmentation/labelme2coco.py
index ffaa593ba..b78e2f801 100755
--- a/examples/instance_segmentation/labelme2coco.py
+++ b/examples/instance_segmentation/labelme2coco.py
@@ -26,7 +26,7 @@ def main():
     )
     parser.add_argument('input_dir', help='input annotated directory')
     parser.add_argument('output_dir', help='output dataset directory')
-    parser.add_argument('--labels', help='labels file')
+    parser.add_argument('--labels', help='labels file', required=True)
     args = parser.parse_args()
 
     if osp.exists(args.output_dir):
diff --git a/examples/instance_segmentation/labelme2voc.py b/examples/instance_segmentation/labelme2voc.py
index 473664e20..366233bf0 100755
--- a/examples/instance_segmentation/labelme2voc.py
+++ b/examples/instance_segmentation/labelme2voc.py
@@ -21,7 +21,7 @@ def main():
     )
     parser.add_argument('input_dir', help='input annotated directory')
     parser.add_argument('output_dir', help='output dataset directory')
-    parser.add_argument('--labels', help='labels file')
+    parser.add_argument('--labels', help='labels file', required=True)
     args = parser.parse_args()
 
     if osp.exists(args.output_dir):
diff --git a/examples/semantic_segmentation/labelme2voc.py b/examples/semantic_segmentation/labelme2voc.py
index c36b46e75..7695de905 100755
--- a/examples/semantic_segmentation/labelme2voc.py
+++ b/examples/semantic_segmentation/labelme2voc.py
@@ -21,7 +21,7 @@ def main():
     )
     parser.add_argument('input_dir', help='input annotated directory')
     parser.add_argument('output_dir', help='output dataset directory')
-    parser.add_argument('--labels', help='labels file')
+    parser.add_argument('--labels', help='labels file', required=True)
     args = parser.parse_args()
 
     if osp.exists(args.output_dir):