An optical communication device using a digital coherent reception system includes a phase detector configured to generate, based on a signal obtained in a course of digital signal processing, a phase signal indicating a displacement of a sampling of a reception signal, a clock switch-determiner configured to switch from an reference clock to a clock of transferred data when a value of an amplitude of the phase signal exceeds a given threshold value, and a selector configured to synchronize the sampling of the reception signal and an internal clock of the digital signal processing with the reference clock at start time or signal loss time, and synchronize the sampling of the reception signal and the internal clock with the line clock of the reception signal except for the start time and the signal loss time.