A light source apparatus according to an aspect of the present disclosure includes a substrate having a first surface, a frame, a lid with which the frame is provided, a light emitter that is accommodated in an accommodation space, a wavelength converter that is provided at the substrate, is accommodated in the accommodation space, converts first light emitted from the light emitter into second light having a wavelength different from the wavelength of the first light, and outputs the second light, and a first optical film that is provided in the light path between the light emitter and the wavelength converter, transmits one of the first light and the second light, and reflects the other one of the first light and the second light, and the light emitter emits the first light in such a way that the chief ray of the first light travels along the first surface.