Next, as the switch 23 of the socket 20 connected to the adapter 100 located at each area in the house is turned on to supply electric power to the socket 20, the microcomputer 17 of the adapter 100 activates with electric power supplied from the power supply control circuit 16 (see FIG. 2B). In response, the energizing information transmitter 104 of the adapter 100 generates energizing information including its own serial number and transfers the generated energizing information to the remote monitoring server 200 at the transmission interval stored in the storage area 106 (S14). Subsequently, the energizing information transmitter 104 repeats S14 while power is supplied to the adapter 100 (that is, while power is supplied to the socket 20).

The energizing information reception log recorder 204 in the remote monitoring server 200 records the date and time every time the energizing information is received from the adapter 100 in the reception log at S13. FIG. 9A is a diagram illustrating the reception log stored for each serial number.