To prevent unevenness of learning values of a valve opening position by shortening the time to be required when learning valve opening position by making the valve to abut on a full opening position or a full closing position, in regard to the valve opening control by an actuator.

When an internal combustion engine is in the initializing condition, a throttle valve 11 is driven in a full opening direction or a full closing direction by a step motor 20, and when change quantity of valve opening position to be detected by a throttle opening sensor 15 per the predetermined time becomes zero or reverse of a value up to that time, it is determined that the valve opening reaches an abutting position. When the predetermined number of rebounds at the abutting position is detected, valve opening position in the sampling time just before detecting the predetermined number of rebounds at the maximum valve opening position, the minimum valve opening position or the abutting position is set as a full opening leaning value or a full closing leaning value.