An internal resonator type SHG light source includes a pump light source which emits a pump light; a solid-state laser which absorbs the pump light and which emits a fundamental wave; an output mirror provided so as to face the solid-state laser, which forms a resonator together with the solid-state laser; a wavelength conversion element provided in the resonator, which converts the fundamental wave into a harmonic wave; a detector which detects a temperature of the wavelength conversion element; and a rotating unit which changes an incident angle of the fundamental wave on the wavelength conversion element by rotating the wavelength conversion element, wherein the rotating unit rotates the wavelength conversion element according to the temperature of the wavelength conversion element as detected by the detector.