PURPOSE: To always automatically adjust the optical axis of a head lamp in the appropriate direction.

CONSTITUTION: When the light switch 31 of a head lamp 1 is ON and the lamp is directed downward and the vehicle speed V reaches a prescribed vehicle speed, the vehicle is running in the environment in which the vehicle can run at a certain speed, and there is possibility that a light emitted only from a head-on car enters this vehicle. When a quantity of light radiated to the vehicle is judged to be over a prescribed value by a light sensor 3, it is judged to be caused by a head-on car, and the optical axis of the head lamp is controlled so as to enable to change the direction left.