A diffusion part diffuses an optical signal emitted from the end face of an optical fiber of an input light guide. An input reflection part reflects the optical signal diffused by the diffusion part in the direction of an output reflection part. A transparent medium guides the optical signal reflected by the input reflection part in the direction of the output reflection part. Output reflection parts reflect optical signals guided in the transparent media in the direction of optical fibers of output light guides. The optical signal reflected by the output reflection part is incident on the end face of the optical fiber and is transmitted over the output light guide.