A light source is movable between a reference position located on an optical axis on the rear side of a rear side focal point of a projection lens and a forward shift position located on the forward side of the reference position. At a predetermined position of the reflecting surface of a reflector on the lower side of the optical axis, an auxiliary reflecting surface having a vertical section of substantially an elliptical shape is formed which has a first focal point set at the center of the light source at the forward shift position, and a second focal point set at the rear side focal point of the projection lens.