PROBLEM TO BE SOLVED: To stabilize a color tone of illumination light including fluorescent light by preventing heat generation in a fluorescent body.SOLUTION: Excitation light from an excitation light source 30 is made incident on a fluorescent body 42. The fluorescent body 42 absorbs the excitation light and excites and emits green fluorescent light. The green fluorescent light is emitted from the same plane as an incidence plane of the excitation light. Heat generation of the fluorescent body 42 is radiated by a heat radiation part 46 provided on a plane opposite from the incidence plane of the excitation light. The green fluorescent light emitted from the fluorescent body 42 is combined with first blue light, second blue light, and red light from a first blue light source 60, a second blue light source 61, and a red light source 62. The combined light is irradiated into a subject through a light guide 25. The light quantity of the first blue light, the second blue light, the green fluorescent light, and the red light is monitored by four photosensors 74a to 74d, respectively. Respective light sources 30, 60 to 62 are subjected to light quantity control on the basis of this monitoring result.
