An automatic transmission is provided. One embodiment of the automatic transmission may include a valve body including control valves for hydraulically controlling a friction engaging element provided within said transmission. The automatic transmission may further include an electric control unit located on said valve body for controlling gear shifting of said automatic transmission. The automatic transmission may further include a transmission case having a peripheral wall for at least partially enclosing a gear shift mechanism and an outer wall provided adjacent to said peripheral wall, wherein said electric control unit is located within a containing space surrounded by said peripheral wall, said outer wall and said valve body.