To provide a headlight installed with a discharge lamp and especially with an electromagnetic shield that is simple structured and easy to produce provided at the location of the lamp.

This headlight has a mirror 20 attached with a discharge lamp 10, a mask 30 arranged in front of the discharge lamp 10, and a conductive shield plate 40 stretched along the rear side of the mirror 20. The mask 30 is made of conductor and connected to a fixed electric potential that catches the parasitic electromagnetic field radiated forward from the discharge lamp 10. The shield plate 40 is stretched along the rear side of the mirror 20 and constructed as a cover connected to the fixed electric potential. By this, the electromagnetic conformity concerning with the headlight using the discharged lamp can be secured.