diff --git a/CMakeLists.txt b/CMakeLists.txt
index d786752..1d91b0e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,6 +1,6 @@
 cmake_minimum_required(VERSION 2.6...3.0.2)
 
-project(xbyak LANGUAGES CXX VERSION 6.65)
+project(xbyak LANGUAGES CXX VERSION 6.66)
 
 file(GLOB headers xbyak/*.h)
 
diff --git a/meson.build b/meson.build
index 971126b..f296532 100644
--- a/meson.build
+++ b/meson.build
@@ -5,7 +5,7 @@
 project(
 	'xbyak',
 	'cpp',
-	version: '6.65',
+	version: '6.66',
 	license: 'BSD-3-Clause',
 	default_options: 'b_ndebug=if-release'
 )
diff --git a/readme.md b/readme.md
index 5052589..0fa16fa 100644
--- a/readme.md
+++ b/readme.md
@@ -1,5 +1,5 @@
 
-# Xbyak 6.65 [![Badge Build]][Build Status]
+# Xbyak 6.66 [![Badge Build]][Build Status]
 
 *A C++ JIT assembler for x86 (IA32), x64 (AMD64, x86-64)*
 
diff --git a/readme.txt b/readme.txt
index ed5a8ea..e92304e 100644
--- a/readme.txt
+++ b/readme.txt
@@ -1,5 +1,5 @@
 
-    C++用x86(IA-32), x64(AMD64, x86-64) JITアセンブラ Xbyak 6.65
+    C++用x86(IA-32), x64(AMD64, x86-64) JITアセンブラ Xbyak 6.66
 
 -----------------------------------------------------------------------------
 ◎概要
diff --git a/xbyak/xbyak.h b/xbyak/xbyak.h
index 2a9c031..86372a0 100644
--- a/xbyak/xbyak.h
+++ b/xbyak/xbyak.h
@@ -155,7 +155,7 @@ namespace Xbyak {
 
 enum {
 	DEFAULT_MAX_CODE_SIZE = 4096,
-	VERSION = 0x6650 /* 0xABCD = A.BC(.D) */
+	VERSION = 0x6660 /* 0xABCD = A.BC(.D) */
 };
 
 #ifndef MIE_INTEGER_TYPE_DEFINED
diff --git a/xbyak/xbyak_mnemonic.h b/xbyak/xbyak_mnemonic.h
index 84d83cb..13e52e1 100644
--- a/xbyak/xbyak_mnemonic.h
+++ b/xbyak/xbyak_mnemonic.h
@@ -1,4 +1,4 @@
-const char *getVersionString() const { return "6.65"; }
+const char *getVersionString() const { return "6.66"; }
 void aadd(const Address& addr, const Reg32e &reg) { opModM(addr, reg, 0x0F, 0x38, 0x0FC); }
 void aand(const Address& addr, const Reg32e &reg) { db(0x66); opModM(addr, reg, 0x0F, 0x38, 0x0FC); }
 void adc(const Operand& op, uint32_t imm) { opRM_I(op, imm, 0x10, 2); }