diff --git a/chainerrl/distribution.py b/chainerrl/distribution.py
index 0cf8e4ce8..cda0dc9b2 100644
--- a/chainerrl/distribution.py
+++ b/chainerrl/distribution.py
@@ -19,13 +19,6 @@
 from chainerrl.functions import mellowmax
 
 
-def _wrap_by_variable(x):
-    if isinstance(x, chainer.Variable):
-        return x
-    else:
-        return chainer.Variable(x)
-
-
 def _unwrap_variable(x):
     if isinstance(x, chainer.Variable):
         return x.array
@@ -263,8 +256,8 @@ class GaussianDistribution(Distribution):
     """Gaussian distribution."""
 
     def __init__(self, mean, var):
-        self.mean = _wrap_by_variable(mean)
-        self.var = _wrap_by_variable(var)
+        self.mean = chainer.as_variable(mean)
+        self.var = chainer.as_variable(var)
         self.ln_var = F.log(var)
 
     @property
@@ -324,7 +317,7 @@ class ContinuousDeterministicDistribution(Distribution):
     """
 
     def __init__(self, x):
-        self.x = _wrap_by_variable(x)
+        self.x = chainer.as_variable(x)
 
     @cached_property
     def entropy(self):