diff --git a/chainer/functions/math/sqrt.py b/chainer/functions/math/sqrt.py
index fd2531c130bc..36db23bf89b2 100644
--- a/chainer/functions/math/sqrt.py
+++ b/chainer/functions/math/sqrt.py
@@ -29,7 +29,7 @@ def backward(self, indexes, grad_outputs):
         return gy / (gx * 2.0),
 
 
-class Rsqrt(function_node.FunctionNode):
+class RsqrtGPU(function_node.FunctionNode):
 
     @property
     def label(self):
@@ -41,16 +41,10 @@ def check_type_forward(self, in_types):
             in_types[0].dtype.kind == 'f',
         )
 
-    def forward(self, inputs):
+    def forward_gpu(self, inputs):
         self.retain_inputs((0,))
         x, = inputs
-        xp = cuda.get_array_module(x)
-        dtype = x.dtype
-        if xp is numpy:
-            out = xp.reciprocal(xp.sqrt(x, dtype=dtype), dtype=dtype)
-        else:
-            # CuPy provides `rsqrt` which is faster than `1.0 / sqrt(x)`.
-            out = cuda.cupyx.rsqrt(x, dtype=dtype)
+        out = cuda.cupyx.rsqrt(x, dtype=x.dtype)
         return utils.force_array(out),
 
     def backward(self, indexes, grad_outputs):
@@ -91,4 +85,9 @@ def rsqrt(x):
 
     .. seealso:: :func:`~chainer.functions.sqrt`
     """
-    return Rsqrt().apply((x,))[0]
+    xp = cuda.get_array_module(x)
+    if xp is numpy:
+        return 1.0 / sqrt(x)
+
+    # CuPy provides `rsqrt` which is faster than `1.0 / sqrt(x)`.
+    return RsqrtGPU().apply((x,))[0]