An object of the present invention is to control according to a vehicle height an auxiliary device provided in a vehicle. A motorcycle 1 having a damper 10A interposed between a vehicle body and an axle includes vehicle height detection means 80 for detecting a vehicle height, with this vehicle height detection means being provided in the damper 10A in an auxiliary manner. The optical axis of a headlight 210, which is an exemplar auxiliary device provided in the vehicle, is controlled based on a detection signal from the vehicle height detection means 80.