A light source apparatus is provided with a prismoidal light source housing having a first inclined surface formed of a dichroic mirror which transmits light of a wavelength less than 600 nm and reflects light of a wavelength of 600 nm or more, a second inclined surface opposed to the first inclined surface and formed of a dichroic mirror which transmits light of a wavelength of 600 nm or more and reflects a light of a wavelength less than 600 nm, green LEDs and blue LEDs are arranged on an external surface of the first inclined surface, and red LEDs which are arranged on an external surface of the second inclined surface.