diff --git a/chainercv/links/model/faster_rcnn/utils/bbox2loc.py b/chainercv/links/model/faster_rcnn/utils/bbox2loc.py
index 94ebe6c385..4ce52f2df9 100644
--- a/chainercv/links/model/faster_rcnn/utils/bbox2loc.py
+++ b/chainercv/links/model/faster_rcnn/utils/bbox2loc.py
@@ -54,6 +54,10 @@ def bbox2loc(src_bbox, dst_bbox):
     base_ctr_y = dst_bbox[:, 0] + 0.5 * base_height
     base_ctr_x = dst_bbox[:, 1] + 0.5 * base_width
 
+    eps = xp.finfo(height.dtype).eps
+    height = xp.maximum(height, eps)
+    width = xp.maximum(width, eps)
+
     dy = (base_ctr_y - ctr_y) / height
     dx = (base_ctr_x - ctr_x) / width
     dh = xp.log(base_height / height)