A light source device includes: a holder that has a first surface and a second surface located higher than the first surface, and is an integral structure; a semiconductor light-emitting device on the first surface; an optical element unit that is disposed above the semiconductor light-emitting device, and has a reflective surface that inclines with respect to the first surface and reflects emitted light from the semiconductor light-emitting device; and a phosphor optical element that is disposed on the second surface and irradiated with reflected light from the optical element unit.