To establish the consistency of the monitoring relation between a monitoring PC(personal computer) and a monitored server.

A monitoring registering means 11 which is regularly started by a regular monitoring registering means 13 acquires an IP(internet protocol) from a monitored server name existing in a monitored server table 12 and transmits a monitoring registration request to a monitored server 2a. A monitoring registration request receiving means 21 receives the monitoring registration request and registers the IP address of a monitoring PC 1a with a monitoring PC table 22. When a failure monitoring means 23 detects a failure, a failure signaling means 24 acquires the IP address of the monitoring PC 1a existing in the table 22 and signals the failure to the monitoring PC 1a.