To eliminate a space for adjusting an optical axis, which is provided between an extension and a lamp unit to adjust the optical axis of a headlight. An extension and a lamp unit are contained in a housing. The circumference of the lamp unit is joined to the extension, whereby the lamp unit is fixed to the extension so as to eliminate a space between the circumference of the lamp unit and the extension. The extension is coupled to the housing via an optical axis adjuster. The optical axis adjuster makes the extension and the lamp unit tilt integrally, thereby adjusting the optical axis. Thus, the optical axis is adjustable although a conventional space for adjusting the optical axis is not provided, whereby the appearance of the headlight is improved.