To prevent occurrence of transmission shock at the time of automatic transmission by reducing engine output while keeping high responsiveness without causing troubles such as deterioration of exhaust performance.

Operation of an internal combustion engine 1 is controlled by an engine control unit 6 which has a determination part 61 which determines generation of torque reduction requirement at the time of automatic transmission, a memory 63 which stores table or map for controlling actuation of electromagnetic actuators 13, 14, and a spark advance rate determination part 62 which calculates the spark advance rate of an EVO (a starting timing of opening an exhaust valve 10) according to obtained parameters. When torque reduction requirement occurs at the time of automatic transmission, the EVO is adjusted according to necessity.