A light source apparatus includes a primary light source that emits primary light, a diffusing member that diffuses and converts the primary light into diffused light, a reflection portion that regularly reflects or diffuse-reflects and converts the diffused light into reflected light, and an emission portion that emits the reflected light to an outside. A portion of the primary light is converted in an order of the diffused light and the reflected light and emitted to the outside from the emission portion in a state of the reflected light.