An optical receiver comprising: first combining means for outputting first combined light by combining local light of first polarization and signal light of second polarization that is orthogonal to the first polarization; first conversion means for converting the first combined light to a first electric signal; first polarization means for allowing a component of polarization plane having an angle of 45 degrees relative to each of polarization planes of the first polarization and the second polarization to pass through; second conversion means for converting a component of the first combined light that has passed through the first polarization means to a second electric signal; first delay means for delaying light of the first polarization or the second polarization by 1/4 wavelength; second polarization means for allowing a component of polarization plane having an angle of 45 degrees relative to each of polarization planes of the first polarization and the second polarization to pass through; third conversion means for converting a component of the first combined light that has passed through the first delay means and the second polarization means to a third electric signal; branching means for outputting a fourth electric signal and a fifth electric signal by branching the first electric signal; first subtraction means for subtracting the fourth electric signal from the second electric signal; and second subtraction means for subtracting the fifth electric signal from the third electric signal; wherein the first combining means is configured to output the first combined light to each of the first conversion means , the first polarization means , and the first delay means . first combining means for outputting first combined light by combining local light of first polarization and signal light of second polarization that is orthogonal to the first polarization; first conversion means for converting the first combined light to a first electric signal; first polarization means for allowing a component of polarization plane having an angle of 45 degrees relative to each of polarization planes of the first polarization and the second polarization to pass through; second conversion means for converting a component of the first combined light that has passed through the first polarization means to a second electric signal; first delay means for delaying light of the first polarization or the second polarization by 1/4 wavelength; second polarization means for allowing a component of polarization plane having an angle of 45 degrees relative to each of polarization planes of the first polarization and the second polarization to pass through; third conversion means for converting a component of the first combined light that has passed through the first delay means and the second polarization means to a third electric signal; branching means for outputting a fourth electric signal and a fifth electric signal by branching the first electric signal; first subtraction means for subtracting the fourth electric signal from the second electric signal; and second subtraction means for subtracting the fifth electric signal from the third electric signal; wherein the first combining means is configured to output the first combined light to each of the first conversion means , the first polarization means , and the first delay means . <EOS>