To switch between a passing light distribution and a running light distribution by moving a part concerned in formation of a light distribution characteristic such as a light source and a reflector.

In this headlight for a vehicle a driving part 5 of a vehicle headlight 1 comprises a motor 51; a first spring 55 for applying a one-side force for positioning a part to a passing light distribution position, meshing gears 52, 53 to move the part to a running light distribution position by the motor 51 against the one-side force of the first spring 55; a second spring 56 for applying a one-side force for mashing the engaging gears 52, 53; and a solenoid 57 for dismeshing the engaging gears 52, 53 against the one-side force of the second spring 56 when it is operated. Thus, the motor drive advantageously reduces electric power consumption. When a trouble occurs, a passing light distribution is certainly set back by the first spring 55 and the short-time operated solenoid 57.