To save power consumption by reducing dependence on an electric control system, and then by increasing the degree of freedom in design of light distribution in a vehicular headlight for scanning forward of a vehicle by reflected light of a mirror.

At a base 5 of a mirror unit 4, a downsized mirror 13 and a large-sized mirror 14 are installed. By making a reflection area different from each other, a relatively small inertia moment is set to the downsized mirror 13, and a relatively large inertia moment is set to the large-sized mirror 14. In a first scanning actuator 17, the downsized mirror 13 is reciprocally rotated, and the whole illuminated region is scanned by the reflected light of the downsized mirror 13 in the horizontal direction. In a second scanning actuator 18, the large-sized mirror 14 is reciprocally rotated, and a part of the illuminated region is scanned by the large-sized mirror 14 in the horizontal direction.