PURPOSE: To make the control time constant even when lots of control devices are employed by providing a function code of the same application device to each control device and controlling simultaneously the same application devices.

CONSTITUTION: In controlling the same application devices simultaneously, a control unit 5 sends a control signal according to a prescribed format. Each control device receives the said signal carried through an electric lamp line 10 to judge whether the text mode is the multiple address mode or not, and when the mode is the multiple address code, whether or not the function code is equal to one's own function code is judged, and when they are equal, the processing according to the control mode at the end of the format is applied. When the mode is not the multiple address mode, or when the function code is not one's own assigned code, no processing is applied.