A light source apparatus includes a light conversion unit converting primary light into secondary light. The light conversion unit includes a light conversion member, a holder and a reflection member. The holder includes an incidence portion through which the primary light enters and an exit portion through which at least part of the secondary light exits in a direction crossing an optical axis of the primary light. The light conversion member is arranged on the optical axis of the primary light. Part of the secondary light allowed to exit from the light conversion member in a direction different from a direction toward the exit portion is reflected by the reflection member and exited from the exit portion. The ratio of reentering to the light conversion member is reduced.