diff --git a/ChangeLog b/ChangeLog
index 2ba0276698..d24faa28c4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Fri Jan  6 23:11:20 2012  Ayumu AIZAWA  <ayumu.aizawa@gmail.com>
+
+	* include/ruby/version.h: RUBY_API_VERSION 2.0.0
+
 Fri Jan  6 12:24:11 2012  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* object.c (rb_inspect): raises Encoding::CompatibilityError if the
diff --git a/include/ruby/version.h b/include/ruby/version.h
index 458efff320..b41b64fe66 100644
--- a/include/ruby/version.h
+++ b/include/ruby/version.h
@@ -30,9 +30,9 @@
 #define RUBY_BIRTH_DAY 24
 
 /* API version */
-#define RUBY_API_VERSION_MAJOR 1
-#define RUBY_API_VERSION_MINOR 9
-#define RUBY_API_VERSION_TEENY 1
+#define RUBY_API_VERSION_MAJOR 2
+#define RUBY_API_VERSION_MINOR 0
+#define RUBY_API_VERSION_TEENY 0
 #define RUBY_API_VERSION_CODE (RUBY_API_VERSION_MAJOR*10000+RUBY_API_VERSION_MINOR*100+RUBY_API_VERSION_TEENY)
 
 #ifdef RUBY_EXTERN