A light source apparatus, configured to introduce light into an endoscope connected thereto, includes a housing, a plurality of light sources supported movably relative to the housing, the light sources being configured to emit light, a light introducing unit configured to introduce, into the endoscope, the light emitted by an intended one of the light sources which is located in such a position that an optical axis thereof corresponds to an optical axis of the light introducing unit, a detector configured to detect a misalignment between the optical axis of the light introducing unit and the optical axis of the intended light source, and a light source moving unit configured to move the intended light source to such a position that the optical axis of the intended light source corresponds to the optical axis of the light introducing unit when the misalignment is detected by the detector.
