To enable stable engagement (conditions) between a rack and a pinion of a driving force transmission mechanism.
The headlamp includes semiconductor light sources 2U, 2D, a fixed reflector 3 having reflecting surfaces 10U, 10D, movable reflectors 4U, 4D having reflecting surfaces 12U, 12D, a solenoid 5, and a driving force transmission mechanism 6. The driving force transmission mechanism 6 includes a rack 14 fixed to the solenoid 5, and pinions 15U, 15D fixed to the movable reflectors 4U, 4D. The tooth parts 17U, 17D of the rack 14 with which the pinions 15U, 15D are engaged to form a part of an arc shape of a circle with the center O of the rack 14 fixed with the solenoid 5 as a center. As a result, stable engagement (conditions) can be ensured between the rack 14 and pinions 15U, 15D of the driving force transmission mechanism 6.