PURPOSE: To widely decrease the number of wirings, to shorten a wiring-length and to easily assemble by equipping a control circuit part to modulate control signal data, superimpose them on a commercial power source and transmit them to plural terminal equipments through power lines and receiving circuit parts provided for the respective terminal equipments.

CONSTITUTION: The control signal data are modulated by a control circuit part 2, superimposed on a commercial power source 1, transmitted to the plural terminals through the power lines and the control signal data are received by receiving circuit parts 10-14 provided for the respective terminals. Consequently, a special wiring for the transmission of the control signal data is unnecessary and it is sufficient to simply wire the power lines to the respective terminal equipments. Thus, power and the control signal data are sent simultaneously, therefore, the number of wirings are widely decreased. the wiring-length is shortened and the assembling is made easier.