A light source unit emits light in a plurality of wavelength ranges. The light source unit can change the light emission ratio of light in each wavelength range. In a case where the switching of first illumination light having a first light emission ratio and second illumination light having a second light emission ratio different from the first light emission ratio is performed, switching-period-illumination light having a switching-period-light-emission ratio different from the first light emission ratio and the second light emission ratio is emitted in a switching period of at least one or more frames.
