diff --git a/jsk_recognition_utils/python/jsk_recognition_utils/visualize.py b/jsk_recognition_utils/python/jsk_recognition_utils/visualize.py
index bb28ce2be3..e32a167f00 100644
--- a/jsk_recognition_utils/python/jsk_recognition_utils/visualize.py
+++ b/jsk_recognition_utils/python/jsk_recognition_utils/visualize.py
@@ -77,6 +77,7 @@ def get_tile_shape(img_num):
             x_num += 1
         return x_num, y_num
 
+    imgs = [img for img in imgs if img is not None]
     if tile_shape is None:
         tile_shape = get_tile_shape(len(imgs))