A controller is provided, which detects operating conditions of an internal combustion engine on the basis of detection results from a group of sensors and drives an actuator that modifies an opening position of a wastegate valve on the basis of the operating conditions. When driving the wastegate valve to a fully closed opening, the controller initially drives the actuator toward a preset provisional fully closed position, and after determining on the basis of a detection result from a position sensor that an actual opening of the wastegate valve has reached the provisional fully closed opening, switches a target opening to the fully closed opening and drives the actuator accordingly.