To enable a load device fed by an uninterruptible power supply to properly execute shutdown processing by connecting the uninterruptible power supply and the load device through a network.

Communicating means 49 of uninterruptible power supplies 2 and 3 communicate with the load device 4 to which the uninterruptible power supplies 2 and 3 themselves feed through the network 5. A UPS storing means 47 stores a waiting time from the time the power abnormality of an AC power source 6 is detected and notified until the time the shutdown of the load device 4 is started. A notifying means 48 notifies the communicating means 49 of a remaining time to the start of the shutdown in a period from the time the power abnormality of the AC power source 6 is detected and notified until the time corresponding to the waiting time (67) stored in the UPS storing means 47 elapses.

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