A polarization multiplexing optical receiver according to the invention includes a polarization splitting unit receiving polarization multiplexed lights which are modulated according to a first input signal and a second input signal including respective identifier, and splitting the polarization multiplexed light into a first polarized received light and a second polarized received light, a pair of photoelectric conversion units, a demodulation unit performing symbol recognition about the first received signal and the second received signal, and outputting a first demodulated signal and a second demodulated signal, an identifier detecting unit detecting the identifiers from the first demodulated signal and the second demodulated signal, and a delay compensation unit calculating a delay difference between the first demodulated signal and the second demodulated signal based on the identifiers, and inserting delay time corresponding to the delay difference into the first demodulated signal or the second demodulated signal.