On the other hand, the warning condition establishment determination unit 208 in the remote monitoring server 200 continuously monitors the energizing state log of each adapter 100 registered by the user and repeats determining whether or not the warning condition configured by the user is met at S15. More specifically, the remote monitoring server 200 periodically determines, for the light bulbs 30 connected to all adapters 100 registered by the user, whether or not an elapsed time period during when the energizing state stays at the same state reaches a time period that is configured as the configured warning condition (i.e., time). When the warning condition establishment determination unit 208 determines that the waning condition is met, the warning information transmitter 209 transfers warning information to the warning destination preregistered by the user using e-mail at S16.

In alternative to or in addition to sending warning information by e-mail, the remote monitoring server 200 may transmit warning information to the user terminal 40 that logs into the remote monitoring service by push notification. In alternative to or in addition to a policy that the warning information is transmitted when the condition that the energizing states of all sockets 20 remain unchanged, the remote monitoring server 200 may adopt a policy that warning information is transferred based on the energizing state of the socket 20 located at a specific area. Examples of such policy include the example case in which warning information is transferred when a frequency in changes in the energizing state of the socket 20 of the lighting of the lavatory is equal to or more than a predetermined frequency (i.e., the person to be observed goes to the lavatory frequently.)