To solve the problem that a computer independent of a power supply device and a dedicated interface circuit for connecting both the power supply device and the computer are required when remotely operating the start/stop of the power supply device used in a personal computer and a server.

A small server having a web server, a mail server, and a firewall function is built in the power supply device, so that only by preparing a space for the power supply device, the power supply device can be remotely started/stopped, a frozen state of the personal computer and the server can be monitored, the frozen state can be restored automatically or by an instruction from the outside, and the state of the power supply device can be monitored and reported.