In general aspect, a white excitation light generating device can include a fluorescent excitation light source that generates fluorescent excitation light, a first light source that generates first monochromatic light of a first wavelength different from a wavelength of the fluorescent excitation light, a second light source that generates second monochromatic light of a second wavelength different from the wavelength of the fluorescent excitation light and the first wavelength, a spectrophoto sensor that measures tristimulus values of at least one of the fluorescent excitation light, the first monochromatic light, and the second monochromatic light, and a controller that adjusts an output of at least one of the fluorescent excitation light source, the first light source, and the second light source on the basis of the measured tristimulus values.