An optical transceiver 1 comprises first and second pseudo-random pattern generators 23 and 28 for generating a pseudo-random pattern signal, which are placed in a transmitting side path 6 and in a receiving side path 11 of the optical transceiver 1, respectively; first and second pseudo-random pattern detectors 21 and 26 for evaluating an inputted pseudo-random pattern signal, which are placed in the transmitting side path 6 and in the receiving side path 11 of the optical transceiver 1, respectively; a first loopback path 31 that loops back from a multiplexing circuit 3 to a demultiplexing circuit 8; and a second loopback path 32 that loops back from a light-electricity converter 7 to an electricity-light converter 4.