A light source apparatus includes an excitation light shining device for emitting excitation light, a rotational wheel device including a rotational wheel including a filter area for transmitting light in a predetermined wavelength range differing from a wavelength range of the excitation light and reflecting the excitation light and a direction-changing transmission area for transmitting the excitation light while changing a direction thereof, and a luminescent light emission device which receives the excitation light reflected on the filter area to thereby emit luminescent light including the light in the predetermined wavelength range towards the filter area, and the rotational wheel device is disposed so that an axis of the excitation light which passes through the direction-changing transmission area and an axis of the luminescent light in the predetermined wavelength range which passes through the filter area are superposed on each other.