To provide an economical optical communication system by reducing optical components to a minimum level.

In a subscriber home 5 which is a local station, a modulator 7 is provided for modulating input light corresponding to a bias signal impressed from a bias circuit 10 and outputting it as output light. At the output terminal of the light modulator 7, a reflecting film is provided for reflecting light from the modulator 7 and inputting it to the output terminal thereof. A down optical signal 2 is defined as input light and the output light of the modulator 7 is defined as an up optical signal 3. The modulator 7 is provided with a PIN layer and a pair of electrodes provided on both faces of the PIN layer for impressing bias signals and a reflecting film 8 is provided on one of both end faces of the PIN layer so that input light can be inputted and output light can be outputted on the other face. Thus, it is not necessary to provide an optical component such as a laser diode ordinarily used in the subscriber home 5 and system cost reduction can be attained.