An optical combiner 3 includes a plurality of incoming optical fibers 10, an outgoing optical fiber 20, and a plurality of bridge fibers 60, 50 provided between the plurality of incoming optical fibers 10 and the outgoing optical fiber 20, the plurality of bridge fibers 60, 50 being optically coupled to each other. In the bridge fibers 60, 50, a ratio of the outer diameter of a core 61, 51 to the outer diameter of a cladding 62, 52 is smaller in a bridge fiber located more apart from the incoming optical fiber 10.