A characteristic compensation method includes obtaining compensation information when degradation of a transmission characteristic of an optical transmission path of a received light signal is compensated for by using digital signal processing with respect to an electric signal obtained by photoelectrically converting the light signal, calculating an compensation value for a characteristic compensation device that optically compensates for degradation of the transmission characteristic to start characteristic compensation, based on the compensation information with respect to the light signal, setting the compensation value in the characteristic compensation device, and switching a state in which compensation is done using the digital signal processing to a state in which compensation is done using the characteristic compensation device after the setting of the compensation value is completed.