diff --git a/docs/en/source/conf.py b/docs/en/source/conf.py
index ab7672b..f374756 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'
+version = '1.1-dev'
 # The full version, including alpha/beta/rc tags
-release = '1.0.0'
+release = '1.1-dev'
 
 
 # -- General configuration ---------------------------------------------------
diff --git a/docs/ja/source/conf.py b/docs/ja/source/conf.py
index 060982b..878933e 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'
+version = '1.1-dev'
 # The full version, including alpha/beta/rc tags
-release = '1.0.0'
+release = '1.1-dev'
 
 
 # -- General configuration ---------------------------------------------------
diff --git a/pyproject.toml b/pyproject.toml
index 6b942c3..aa69870 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "HTP-tools-cif2x"
-version = "1.0.0"
+version = "1.1-dev"
 description = "High-ThroughtPut calculation tools"
 authors = ["HTP-tools developers <htp-tools-dev@issp.u-tokyo.ac.jp>"]
 license = "GPL-3.0-or-later"