An optical combiner includes: a plurality of first input optical fibers that each include a core; a bridge fiber that includes a bridge input surface connected to the cores of the plurality of first input optical fibers, a diameter reduction portion having a diameter that decreases away from the bridge input surface along an optical axis of the optical combiner, and a bridge output surface located opposite to the bridge input surface along the optical axis; an intermediate optical fiber that includes a core connected to the bridge output surface of the bridge fiber; a second input optical fiber that includes a core; and an output optical fiber that includes a first optical waveguide connected to the core of the intermediate optical fiber, and a second optical waveguide connected to the core of the second input optical fiber.