PROBLEM TO BE SOLVED: To manage a power unit for non-power cut by means of communication through the use of a power line and an information unit by providing a means communicating information with the power line as a route. SOLUTION: A power line transmission/reception means 10a is connected to UPS 1a and a signal is transported by using a frequency which is sufficiently higher than the frequency of a commercial AC power source 2. A signal inputted from the direction of a power plug 6a is received by a power cable 7a. The reception signal is transmitted to a control circuit 12 and the control circuit 12 analyzes the content of the signal. A control signal against UPS 1a is discriminated from a signal against the other device. In the case of the control signal against UPS 1a, the control circuit 12 controls UPS 1a. A computer 8a which is the load of UPS 1a and is a management object incorporates a power line transmission communication means 20a and the signal is transmitted by using the power line transmission communication means 20a. A computer 23a being a management source, and the computers 8a and 8b being the management objects and UPS 1a-c are connected by the power line transmission communication means 20a.