A light source apparatus according to the present disclosure includes a first light source section that outputs first light, a second light source section that outputs second light, a first polarization separator that transmits the first light and the second light polarized in a first polarization direction and reflects the first light polarized in a second polarization direction, a second polarization separator that reflects the first light polarized in the first polarization direction, a first diffusion element that diffuses the first light incident from the first polarization separator, a wavelength converter that converts in terms of wavelength the first light and emits third light, and a second diffusion element that diffuses the second light incident from the second polarization separator.