To provide communication equipment which can shorten time required for establishing delay amount synchronization at an interferometer, and to provide its interferometer synchronization coIntrol method.

The communication device is used for an optical communication system where an optical signal is phase modulated to transmit information. The communication device includes an interference means (202), light detection means (204 and 205), separation means (S2102 and S2103), and a delay adjustment means (S2106). The interference means inputs each optical signal coming from a transmission source, and outputs interference output light according to the phase difference of the optical signal to the light detection means. The separation means separates a signal for phase shift determination from a detected signal by the light detection means. The delay adjustment means adjust the delay amount of the interference means based on the signal for phase shift determination.

COPYRIGHT: (C)2011,JPO&INPIT