diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3b5245634..c0d0196fe 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,7 +1,7 @@
 cmake_minimum_required(VERSION 2.6)
 # cmake_minimum_required(VERSION 3.0)
 project(ecell4)
-set(PROJECT_VERSION 4.0.5)
+set(PROJECT_VERSION 4.0.6)
 
 if(ECELL4_ENABLE_PROFILING)
     add_definitions(-pg -O0)
diff --git a/readthedocs/conf.py b/readthedocs/conf.py
index 1614c11a0..3e86a3130 100644
--- a/readthedocs/conf.py
+++ b/readthedocs/conf.py
@@ -11,8 +11,8 @@
 copyright = u'2015-, E-Cell project'
 author = u'Kazunari Kaizu'
 
-version = '4.0.5'
-release = '4.0.5'
+version = '4.0.6'
+release = '4.0.6'
 
 language = None
 
diff --git a/requirements.txt b/requirements.txt
index 1234b1619..341919cdf 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,4 @@
 recommonmark
 numpydoc
 pip>=8.1.2
-ecell>=4.0.5
+ecell>=4.0.6