A light source unit including an LED mounted on an optical axis extending in the longitudinal direction of the vehicle with its light output directed upward, and a reflector is provided above the LED having a first reflecting surface for collecting the light emitted by the LED and reflecting the light generally in the direction of the optical axis Ax. The first reflecting surface is formed in such a manner that a distance L in a vertical direction from the LED to the first reflecting surface is approximately 10 mm in a preferred embodiment.