The light source apparatus is provided with a plurality of light source device disposed in the form of a ring and that emit illumination light toward the central axis of the ring by being lit in a sequential pulsed fashion; a light-guide portion having a light entrance surface rotatably disposed on the central axis and on which the illumination light emitted from the light source devices is incident, and a reflecting surface that reflects the incident illumination light in the direction along the central axis; and a driving device that controls a pulsed-lighting phase range. The driving device controls the pulsed-lighting phase range (W) such that, when the pulsed-lighting phase range (W) is shorter than a maximum-pulse phase range (M), a preceding light-out phase range (F) and a succeeding light-out phase range (R) are provided before and after the pulsed-lighting phase range (W) in the maximum-pulse phase range (M).