To provide an optical communication system that employs an optical fiber as a transmission line of a portable telephone system and can suppress intermodulation distortion in the case that frequency multiplex processing is applied to a portable telephone signal adopting the PDC system and the CDMA system and the processed signal is transmitted through the optical fiber.

The optical communication system of this invention consists of an optical transmitter 1 that optically modulates 1st and 2nd high frequency signals 51, 52 having different frequencies at different optical modulation degrees and transmits the modulated signals to an optical transmission line and of an optical receiver 2 that optically demodulates the optical signal received from the optical transmission line 3, separates the 1st and 2nd high frequencies signals from the demodulated signal, and corrects a level deviation given between both the signals for optical modulation with different optical modulation degrees by individually adjusting the levels of both the signals.