In order to integrally manage computers and peripheral devices at a user site, when a device monitoring server (203a) receives a trouble message from a device, it sends a message indicating this to a device center server (210) via a router (204). If the received message is a trouble message, the device center server (210) controls an event adapter to convert the received message into a format that a center server can process, and transfers the converted message to the center server (110). Upon receiving the message, the center server (110) displays occurrence of a trouble in an event list using an event monitor (110a). The user can simultaneously monitor the versatile computers and peripheral devices by observing the event monitor.