PURPOSE: To communicate picture data or the like at high speed by transmitting and receiving data like picture data between a selected optical communication terminal and a mail unit by an optical signal and transmitting and receiving data like picture data between the mail unit and an external communication terminal through a communication line.

CONSTITUTION: Each optical facsimile terminal 2 is connected to an optical switchboard 1 by a pair of optical fibers 5, and a mail unit 3 is connected to the board 1 by two pairs of optical fibers 6. In such a system, two line wires (public telephone lines or the like) 8 and 9 are connected to the mail unit 3 for the purpose of performing not only facsimile communication between private facsimile terminals 2 but facsimile communication to external general facsimile terminals. Consequently, the optical signal is used to confirm call originating and response, and picture data or the like is transmitted and received by the optical signal. Thus, data is communicated at high speed.