PURPOSE: To prevent a rise in temperature of a lamp body by forming a lamp body and a cover by plastics, respectively, and providing a rib for forming a ventilating part between the both to rapidly release the heat of the lamp body.

CONSTITUTION: When a lamp 26 is lighted, the light from the lamp 26 is reflected and collected by the reflecting surface 15 of the reflector member 22 of a lamp body 11, and radiated from a lighting opening part 12. Then, the lamp body 11 is heated by the lamp 26. An air passage 17 is formed between the inner circumferential surface of the cover 1 and the outer circumferential surface of the lamp body 11 by a rid 5 in the cover 11. Therefore, the heat release of the lamp body 11 is rapidly and effectively performed by the flow of the air in the air passage part 17 from the lighting opening part 12 to the backward. Hence, a rise in temperature of the lamp body 11 is reduced.