A server 200 includes a scenario table in which object to-be-monitored information that indicates one or more network devices A, B and C being objects for failure recovery, failure information for identifying contents of failures, countermeasure information against failures, and frequency information that indicates the number of times of the recoveries from the failures based on the countermeasure information are correspondingly stored. The network device A 300 detects the failure of the network device itself and transmits a failure event to the server 200. The server 200 selects the countermeasure information item in descending order of the frequency information items, by reference to the scenario table, and transmits the selected countermeasure information item to the network device A 300. The server 200 repeats the selections and transmissions of the pertinent information item until the reception of the failure event from the network device A 300 stops.