A first light source module 20 and an irradiation module 50, 70 are mutually combined. By the combination, illumination light corresponding to a purpose of use is emitted. A relative distance between a light source-side emission unit 23 and an irradiation-side incidence portion 51, 71 in an optical axis direction is adjusted as desired in accordance with the irradiation module 50, 70, which is connected to the first light source module 20.
