For a turn lamp unit, a reflecting member is disposed in an inner space formed by a housing and lens section, wherein the reflecting member is fixed to the housing by a screw. The head portion of the screw is disposed inside a screw housing space arranged at the housing, and an opening of the screw housing space is closed by a waterproof moisture-transmission section. Further, since the inner space and screw housing space are communicated with each other through a breathing hole, one end of the breathing hole is continuous with the inside of the screw housing space closed by the waterproof moisture-transmission section, and the other end of the breathing section is continuous with the inside of the inner space.