To provide a monitoring system capable of associating the configuration of the system using simple steps.

Plural power lines provided in a distribution panel are connected to a CT sensor 1 which radio-transmits the detected power value on the power lines. A smart tap 2 inserted into a socket detects a value of the load power in a state that plugs of household electrical appliances are inserted and radio-transmits the detected value of the load power. A tablet terminal apparatus 4 receives the power value of respective power lines transmitted from the CT sensor 1 and the load power value transmitted from the smart tap 2 to detect time-elapse changes of the power values of the respective power lines and time-elapse changes of the respective load power values. When the power value of a power line and a load power value having the time-elapse changes coincide with each other are detected, the CT sensor 1 and the smart tap 2 are associated with each other.