A light source device includes: a semiconductor light-emitting device including a flat-shaped base having a first main surface on a first side and a second main surface and a semiconductor light-emitting element disposed on the first side; a first fixing component having a first through-hole and a first pressing surface that presses the first main surface; and a second fixing component having a second through-hole and a second pressing surface that presses the second main surface. The base is fixed between the first and second pressing surfaces by an engagement between a first inner surface surrounding the first through-hole of the first fixing component and a second outer surface of the second fixing component. A distance between the first and second pressing surfaces is smaller than or equal to a thickness of the base, and a void is formed lateral to the base between the first and second pressing surfaces.