To provide a headlamp that keeps a small load between a rack and a pinion of a driving force transmission mechanism and maintains high positional accuracy for a stop position of a movable reflector.

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 and pinions 15U, 15D. The height H1 of tooth parts 17U, 17D at both ends of the rack 14 is higher than the height H2 of the tooth parts 17U, 17D in the middle part of the rack 14. The load between the rack 14 and pinions 15U, 15D can be kept small, and high accuracy can be maintained for the stop positions of the movable reflectors 4U, 4D.