Vehicle headlight

A vehicle headlight can be configured such that the size of the vehicle headlight which includes a semiconductor laser element (14) employed as a light source is reduced. The vehicle headlight can includes: a projection lens (26) disposed on an optical axis extending in a front-to-rear direction of a vehicle body; a light-emitting device (10) including a semiconductor laser element (14) configured to emit a laser beam and a light-transmitting member (12) configured to absorb and convert the wavelength of at least part of the laser beam from the semiconductor laser element (14); and a first reflection surface (28a) configured to reflect the light from the light-emitting device (10) so as to transmit and project forward the resulting light through the projection lens (26). The vehicle headlight can further include: a light detection unit (74) configured to detect a light beam of a specific color, the light detection unit (74) being disposed between the projection lens (26) and the light-emitting device (10) and below the optical axis; a second reflection surface (28c) configured to reflect the light beam from the light-emitting device (10) toward the light detection unit (74), the second reflection surface (28c) being disposed ahead of the front end of the first reflection surface (28a); and a control unit (80) configured to control the semiconductor laser element (14) in accordance with a detection result provided by the light detection unit (74) so that the semiconductor laser element (14) does not emit the laser beam.