diff --git a/tianshou/data/batch.py b/tianshou/data/batch.py
index 7fddda2..e204151 100644
--- a/tianshou/data/batch.py
+++ b/tianshou/data/batch.py
@@ -19,6 +19,8 @@ def _is_batch_set(obj: Any) -> bool:
         # "for element in obj" will just unpack the first dimension,
         # but obj.tolist() will flatten ndarray of objects
         # so do not use obj.tolist()
+        if obj.shape == ():
+            return False
         return obj.dtype == object and \
             all(isinstance(element, (dict, Batch)) for element in obj)
     elif isinstance(obj, (list, tuple)):