A lamp holder comprises: a resin cover member made of resin and having an open space portion at a place where the light from the lamp body is irradiated; and a cover plate which is made of metal and has a projection window of the cover plate for the light emitted from the lamp body to pass through, and which is fixed to the resin cover member for covering the open space portion of the resin cover member. According to this lamp holder, the cover plate made of metal is provided at a place of the lamp holder where out gas would be most likely to be produced if a resin material were used at such place, preventing a portion of the resin cover member from being provided at such place. This makes it possible to prevent out gas from being produced from the lamp holder.