An optical transmission system includes an optical transmission equipment (100) and an optical receiving device (300; 400). The optical transmission equipment transmits an optical signal from a first adjacent node to a second adjacent node, and includes an optical multiplexing and demultiplexing unit that demultiplexes the optical signal from the first adjacent node into an optical transmission signal to be transmitted to the second adjacent node and an optical demultiplexed signal, and a compensating unit (140) that partially compensates chromatic dispersion in the optical demultiplexed signal. The optical receiving device receives the optical signal from the optical transmission equipment, and includes a converting unit (430) that converts the optical demultiplexed signal the chromatic dispersion of which is partially compensated by the compensating unit (140) into an electric digital signal, and a digital processing uni (440) that compensates chromatic dispersion remaining in the electric digital signal.