Gears are shifted within the Automatic Transmission by switching the oil passage based on the command from ECU and actuating the shift valve. Due to the fuel consumption regulations, the solenoid body was changed from steel to aluminum. The result was a reduction in weight. Additionally, the electromagnetic coil was reduced by increased efficiency through a change in the structure of the magnetic passage of the solenoid. The high thrust force solenoid specification allows a wide range of oil pressure control. The optimization of valve setting ensures oil flow even at low temperature, realizing high response switching of the shift valve.