A light source device which can reliably prevent the displacement of its reflector and a projector including the light source device includes a housing. The housing of the light source device includes: a cover member attached to cover a reflecting portion of a reflector from its front side in a light beam launching direction. The housing also includes a housing body to cover the reflector from its rear side in the light beam launching direction. The cover member and reflector are secured by clip-shaped fixing members to pinch and hold the flange portion of the reflector and the abutting face of the cover member abutting against the flange portion. The fixing members are disposed between the slanted face portions of the housing body and the cover member, and pinched and held therebetween.