To increase a probability that an error correction is successful even when the error correction can not be made so far since a bit error exceeding the error correcting capability of an FEC decoder occurs to a transmission line.

An optical receiver has a first FEC decoder 10a which corrects the error of data of each FEC frame having been synchronized using parity for error correction and decodes the data, a synchronization header correcting unit 10b which corrects the value of a synchronization header which can not be taken theoretically among values of the synchronization header whose decoding by the first FEC decoder 10a has ended in failure into the value of the synchronization header indicative of packet data and/or the value of the synchronization header indicative of idle data, and a second FEC decoder 10c which corrects the error of the FEC data and decodes the data again on the basis of the FEC frame having the synchronization header corrected by the synchronization header correcting unit 10b.