An optical reception apparatus according to the present invention comprises: a branching section that branches an optical signal input thereto into two; first and second delay interferometers arranged on optical paths through which the branched lights are propagated; first and second photoelectric converting sections that receive the output lights from the delay interferometers; a clock recovery circuit for recovering a clock signal based on a data signal output from one of the photoelectric converting sections; a multiplexing section that multiplexes data signals from the photoelectric converting sections in accordance with the clock signal; and a delay interferometer control section that resets operating conditions of the delay interferometers when the frame synchronization is not achieved. Thus, it becomes possible to perform the demodulation processing on the signal light which is differential phase shift keying modulated using a quadrature phase component, utilizing a general-purpose framer.