PROBLEM TO BE SOLVED: To prevent heat generation in a phosphor, and to multiplex fluorescence and the other light of a plurality of wavelengths without using an optical member such as a dichroic prism.SOLUTION: Excitation light from an excitation light source 30 is made incident on a phosphor 42 through a first optical surface 42a. The the phosphor 42 absorbs the excitation light to cause excitation emission of green fluorescence. On a second optical surface 42b on the opposite side of the first optical surface 42a, a substrate 49 for a light source including a first blue light source 45, a second blue light source 46 and a red light source 47 is provided. First blue light, second blue light and red light from the light sources 45-47 are multiplexed with the green fluorescence inside the phosphor 42. The inside of a subject is irradiated with the multiplexed light through the first optical surface 42a or the like. Generated heat in the phosphor 42 is discharged by a heat radiation part 50 provided on the substrate 49 for the light source.
