PURPOSE: To offer the power line carrier system which can clarifies the control coverage, and has high reliability by conducting minimum electric wiring works and also with electric works within ease of cabling into conduits or ducts through the use of existing electric wires.

CONSTITUTION: Block filters 61, 62 showing a low impedance to a high frequency carrier signal for branching breaker side and showing a high impedance to the high frequency carrier signal at its branched power line side are inserted and connected between each branch power line selected as power line carrier control in branch power lines 4, 5 connected to a main electric line via branch breakers 311..., 312... and the said branch power line. Furthermore, a signal passing circuit showing a low impedance to the high frequency carrier signal and showing a high impedance to only a commercial frequency is connected between branch power lines of each floor selected as power line carrier control. The control coverage of the power line carrier system is set to a specific branch power lines in a multi-floor building. Thus, the effect of load equipments of floors and branch power lines independently of the control is eliminated, the reliability of the system is maintained and managed and the system with high reliability is realized.