A light source apparatus according to an aspect of the present disclosure includes a light emitter, a light guide member, a support member having a groove, and a position restriction member. The light guide member has a first surface and a second surface located at sides opposite from each other in a first direction, a third surface and a fourth surface located at sides opposite from each other in a second direction, and a fifth surface and a sixth surface located at sides opposite from each other in a third direction. The groove has a support surface facing the fourth surface, a first wall surface facing the fifth surface and separate from the fifth surface, and a second wall surface facing the sixth surface and separate from the sixth surface. The position restriction member includes a first placement section and a second placement section.