diff --git a/python_module/megengine/functional/__init__.py b/python_module/megengine/functional/__init__.py
index 651037eeba2d28b1842e5ecbae3fbd5139516b93..6b262bfd4612d77132cec74e48f1c73c611cd609 100644
--- a/python_module/megengine/functional/__init__.py
+++ b/python_module/megengine/functional/__init__.py
@@ -21,6 +21,8 @@ from .elemwise import (
     floor,
     greater,
     greater_equal,
+    isinf,
+    isnan,
     less,
     less_equal,
     log,
diff --git a/python_module/megengine/functional/elemwise.py b/python_module/megengine/functional/elemwise.py
index 6bed2d3d833ffa54ecb13336e610c0fed088c30e..2bb59255adcecada7f8ece1191f9cd919a6a82a2 100644
--- a/python_module/megengine/functional/elemwise.py
+++ b/python_module/megengine/functional/elemwise.py
@@ -27,6 +27,8 @@ __all__ = [
     "greater",
     "greater_equal",
     "floor",
+    "isinf",
+    "isnan",
     "less",
     "less_equal",
     "log",
@@ -244,3 +246,49 @@ def clamp(inp: Tensor, lower=None, upper=None) -> Tensor:
             return maximum(inp, lower)
     else:
         return minimum(inp, upper)
+
+
+def isnan(inp: Tensor) -> Tensor:
+    r"""Returns a new tensor representing if each element is NaN or not.
+
+    :param: inp
+    :return: a new tensor representing if each element in :attr:`inp` is NaN or not.
+
+    Examples:
+
+    .. testcode::
+        from megengine import tensor
+        import megengine.functional as F
+
+        x = tensor([1, float("nan"), 0])
+
+        print(F.isnan(x))
+
+    .. testoutput::
+        Tensor([0 1 0], dtype=uint8)
+
+    """
+    return (inp != inp).astype("uint8")
+
+
+def isinf(inp: Tensor) -> Tensor:
+    r"""Returns a new tensor representing if each element is Inf or not.
+
+    :param: inp
+    :return: a new tensor representing if each element in :attr:`inp` is Inf or not.
+
+    Examples:
+
+    .. testcode::
+        from megengine import tensor
+        import megengine.functional as F
+
+        x = tensor([1, float("inf"), 0])
+
+        print(F.isinf(x))
+
+    .. testoutput::
+        Tensor([0 1 0], dtype=uint8)
+
+    """
+    return (abs(inp) == float("inf")).astype("uint8")
diff --git a/python_module/test/unit/functional/test_elemwise.py b/python_module/test/unit/functional/test_elemwise.py
index ef9cf6fad34d1bbcc52856eafaf5a3f00c17f7a6..c02bd58b608039a28b9b84ff8cf531dc43657974 100644
--- a/python_module/test/unit/functional/test_elemwise.py
+++ b/python_module/test/unit/functional/test_elemwise.py
@@ -53,3 +53,13 @@ def test_clamp():
     x = np.linspace(-6, 6, dtype="float32")
     assertTensorClose(F.clamp(tensor(x) + 3, 0, 6).numpy(), np.clip(x + 3, 0, 6))
     assertTensorClose(F.clamp(tensor(x) - 3, -6, 0).numpy(), np.clip(x - 3, -6, 0))
+
+
+def test_isnan():
+    for case in [[1, float("nan"), 0]]:
+        assertTensorClose(F.isnan(tensor(case)), np.isnan(case).astype("uint8"))
+
+
+def test_isinf():
+    for case in [[1, float("inf"), 0]]:
+        assertTensorClose(F.isinf(tensor(case)), np.isinf(case).astype("uint8"))