In a light source system constituted by combining a light source module having a light source and a light source light emitting end, and an irradiation module having an optical connection terminal, a light guide member and a light emitting member and being mechanically detachably attachable to the light source module, when a first light guide route is defined as a route comprising a first light source, a first light source light emitting end (32), a first optical connection terminal (70), a first light guide member (76), and a first light emitting member (78), and when a second light guide route is defined as a route comprising a second light source, a second light source light emitting end (52), a second optical connection terminal (72), a second light guide member (82), and a second light emitting member (88), the first light source light emitting end and the first optical connection terminal are constituted based on desirable first optical specifications, and the second light source light emitting end and the second optical connection terminal are constituted based on desirable second optical specifications, so that the first or second light guide route can be constituted.
