An optical transmission system, phase compensation method, and the light reception device

To compensate for the phase variation caused by the transmission path and the like while suppressing the increase in circuit scale. The optical transmission system includes a pilot symbol detection unit for detecting an intermittently inserted plurality of pilot symbols were in the received complex electric field signal obtained by the coherent detection for the received optical signal, a pilot symbol is detected by the pilot symbol detector , and a reference symbol to a predetermined, and the error signal calculation unit for calculating a complex electrical field error signal indicating the phase variation at each pilot symbol based on the complex electric field error signal the error signal calculation unit is calculated using the filtering , a compensation field signal generating unit that estimates a phase variation between pilot symbols in the received complex electric field signal based on the phase variations between the pilot symbols compensation field signal generating unit is estimated, the phase for performing phase compensation for the received complex electric field signal and a noise compensation unit.