System and method of monitoring the old and the weak living alone

A system for managing a person to be monitored and a method therefor are provided to generate the first warning signal when the power that the person located at a distant place uses is not changed for a predetermined time, and then transmit the generated signal to a terminal of a manager. A control server(300) is connected to a plurality of repeaters(100_1-100_n) in one-to-n relationship(1:n) through a wired/wireless communication network. Each repeater is connected with a plurality of monitoring terminals in one-to-n relationship(1:n) through the wired/wireless communication network. The control server manages a plurality of monitored persons who are dispersedly located. Monitoring data, a warning signal and a power control signal have respectively a terminal identification code which makes the signal accurately transmitted/received among the control server, repeaters and monitoring terminals.