To more easily inhibit a change in chromaticity that occurs at the time of light amount fluctuation of semiconductor light-emitting devices without providing a feedback system. A medical light source device according to the present disclosure includes: a light source part including two or more semiconductor light-emitting devices having wavelengths of emitted light different from each other, the light source part being configured to generate light of predetermined chromaticity by mixing the light emitted from each of the semiconductor light-emitting devices and emitting outward the generated light of the chromaticity as illumination light； and a control unit configured to control a mixing rate of the light emitted from each of the semiconductor light-emitting devices in accordance with a light amount setting value of the illumination light emitted from the light source part, the control unit being configured to keep the chromaticity constant regardless of a light amount of the illumination light.
