To achieve miniaturization and simplification of a structure.

A headlight for a vehicle comprises: a light source unit 11 that has a light source 24; a light amount control mechanism 26 that has a movable shade 29 for switching the blocked amount of light emitted from the power source and an actuator 27 for operating the movable shade; a projection lens 9 that projects the light emitted from the power source; and a lens holder 8 that holds the projection lens. The light amount control mechanism is assembled to the lens holder.