PURPOSE: To perform remote control with simple constitution by interposing control information for controlling a remote transmitter/receiver connected to the same data line between the flag of data and a flag.

CONSTITUTION: A master communication controller 5 starts the transmitter/ receiver 1 through a control signal line 15 and a data inserting and deleting device 3 interposes the control information between the flag of the data on a flag synchronizing data circuit 11 and the flag and sends out the data to the data line 10. The data inserting and deleting device 4 deletes data which is shorter than prescribed minimum data length, so the control information interposed between the flags is deleted and the deleted control information is sent out to a control information data line 14. A slave communication controller 6 receives this control information and starts a transmitter receiver 2 through a control signal line 16 according to the contents of the control 1 information. Thus, the transmitter receivers 1 and 2 are started under the control of the master communication controller 5 to enable communicating operation.