diff --git a/docs/en/source/cif2x/about/index.rst b/docs/en/source/cif2x/about/index.rst
index 1c699f6..de8b1c2 100644
--- a/docs/en/source/cif2x/about/index.rst
+++ b/docs/en/source/cif2x/about/index.rst
@@ -25,7 +25,7 @@ Contributors
 
 This software was developed by the following contributors.
 
--  ver.1.0-beta (Released on 2023/12/08)
+-  ver.1.0-alpha (Released on 2023/12/28)
 
    -  Developers
 
diff --git a/docs/en/source/conf.py b/docs/en/source/conf.py
index 52a03b3..8436f7f 100644
--- a/docs/en/source/conf.py
+++ b/docs/en/source/conf.py
@@ -26,9 +26,9 @@
 # built documents.
 #
 # The short X.Y version.
-version = '1.0-beta'
+version = '1.0-alpha'
 # The full version, including alpha/beta/rc tags
-release = '1.0-beta'
+release = '1.0-alpha'
 
 
 # -- General configuration ---------------------------------------------------
diff --git a/docs/ja/source/cif2x/about/index.rst b/docs/ja/source/cif2x/about/index.rst
index 0f9257b..460b906 100644
--- a/docs/ja/source/cif2x/about/index.rst
+++ b/docs/ja/source/cif2x/about/index.rst
@@ -27,7 +27,7 @@ cif2xは、cifファイルから第一原理計算用の入力ファイルを生
 
 本ソフトウェアは以下の開発貢献者により開発されています。
 
--  ver.1.0-beta (2023/12/08リリース)
+-  ver.1.0-alpha (2023/12/28リリース)
 
    -  開発者
 
diff --git a/docs/ja/source/conf.py b/docs/ja/source/conf.py
index d907cc1..a035120 100644
--- a/docs/ja/source/conf.py
+++ b/docs/ja/source/conf.py
@@ -26,9 +26,9 @@
 # built documents.
 #
 # The short X.Y version.
-version = '1.0-beta'
+version = '1.0-alpha'
 # The full version, including alpha/beta/rc tags
-release = '1.0-beta'
+release = '1.0-alpha'
 
 
 # -- General configuration ---------------------------------------------------