An irradiation module mechanically detachably attached to a light source module includes a first light source light entrance end which allows entry of first light source light from a first light source module, a first light guide member to guide the first light source light entered the first light source light entrance end, a second light source light entrance end which allows entry of second light source light from a second light source module, and a second light guide member to guide the second light source light entered the second light source light entrance end. The first light guide member and the second light guide member have optical specifications which correspond to optical characteristics of the light source light to be guided and in which the optical characteristics are different from each other.
