A light source apparatus for supplying a light guide device incorporated in an endoscope with a light beam is provided. A light emitting device of semiconductor, for example, laser diode generates the light beam. A light homogenizer homogenizes irradiance distribution of the light beam in a radial direction. A short focus lens is disposed between the light homogenizer and the light guide device, for enlarging a divergence angle of the light beam. Furthermore, the light homogenizer is a transparent light guide rod disposed to extend in an optical axis direction of the light beam. A diameter of the light homogenizer is constant in an optical axis direction thereof. The diameter of the light homogenizer is equal to or less than a diameter of the short focus lens.
