The deflection angles of the irradiation of lamps provided at the left and right portions of an automobile are continuously increased in correspondence to the increase of a steering angle until the steering angle reaches a predetermined value. The left and right lamps are held at particular deflection angles respectively when the steering angle is equal to or more than a predetermined steering angle. The value of the particular deflection angle of the lamp on the steering direction side is made larger than that of the lamp on the opposite side. When the deflection angle is small, the left and right lamps are deflected in almost the same state to irradiate the straight traveling direction or the traveling direction of an automobile. When the deflection angle becomes large, the lamp on the steering direction side irradiates the traveling direction and the lamp on the opposite direction irradiates an area in the straight traveling direction.