diff --git a/doc/requirements.txt b/doc/requirements.txt
index 594d6374c..a26dc92a7 100644
--- a/doc/requirements.txt
+++ b/doc/requirements.txt
@@ -1,13 +1,13 @@
 nnabla==1.35.0.dev1
-Sphinx==4.5.0
+Sphinx
 sphinx-rtd-theme
-mock==1.0.1
-pillow==5.4.1
-alabaster>=0.7,<0.8,!=0.7.5
-commonmark==0.8.1
-recommonmark==0.5.0
+mock
+pillow
+alabaster
+commonmark
+recommonmark
 readthedocs-sphinx-ext
-jinja2<3.1.0
+jinja2
 sphinxcontrib-actdiag
 sphinxcontrib-blockdiag
 sphinxcontrib-nwdiag
@@ -16,7 +16,6 @@ sphinxcontrib-seqdiag
 sphinxcontrib-toc
 breathe
 pygments
-funcparserlib==1.0.0a0
+funcparserlib
 tensorflow
 tensorboardX
-
diff --git a/doc/requirements.txt.tmpl b/doc/requirements.txt.tmpl
index b72207059..985458318 100644
--- a/doc/requirements.txt.tmpl
+++ b/doc/requirements.txt.tmpl
@@ -1,13 +1,13 @@
 nnabla==${'.'.join(version.split('.')[:3])}
-Sphinx==4.5.0
+Sphinx
 sphinx-rtd-theme
-mock==1.0.1
-pillow==5.4.1
-alabaster>=0.7,<0.8,!=0.7.5
-commonmark==0.8.1
-recommonmark==0.5.0
+mock
+pillow
+alabaster
+commonmark
+recommonmark
 readthedocs-sphinx-ext
-jinja2<3.1.0
+jinja2
 sphinxcontrib-actdiag
 sphinxcontrib-blockdiag
 sphinxcontrib-nwdiag
@@ -16,7 +16,7 @@ sphinxcontrib-seqdiag
 sphinxcontrib-toc
 breathe
 pygments
-funcparserlib==1.0.0a0
+funcparserlib
 tensorflow
 tensorboardX