An optical combiner 100 includes: fibers for propagation of pumping light 20 configured to propagate pumping light; a fiber for propagation of laser light 10 configured to propagate laser light having a longer wavelength than the pumping light; and a large area fiber 30 having a core 31 and a clad 32 and configured to propagate laser light and pumping light, in which one end surface of the fiber for propagation of laser light 10 and one end surface of the large area fiber 30 are fused, one end surfaces of the fibers for propagation of pumping light 20 and the one end surface of the large area fiber 30 are fused, and the fiber for propagation of laser light 10 and the fibers for propagation of pumping light 20 are not fused to each other.