The optical reception apparatus of the invention branches into two an RZ-DQPSK optical signal input from an optical transmission path via an optical amplifier, respectively sends this to delay interferometers and photoelectric converters on a pair of arms, separately detects a number of generated errors for the signals propagating through the arms in an error-number detection circuit, obtains a difference in the respective number of generated errors in an error-number detector, and controls phase shift in the delay interferometers so that the difference is within a preset tolerance. By so doing, it is possible to realize excellent reception performance by suppressing the occurrence of the burst error.