The failure knowledge storage 5 stores failure knowledge information describing countermeasure command selection information, of which a diversion to a failure other than failures described in a failure countermeasure rule in the rule storage 2 can be surmised. When the failure occurring in the service executor 11 matches the failure described in the failure countermeasure rule, the countermeasure retriever 3 executes the countermeasure command in the failure countermeasure rule on the service executor 11. It is decided whether or not a failure other than the failures described in the failure countermeasure rule matches a failure described in the failure knowledge information in the failure knowledge storage 5. When there is a match, the countermeasure command is read out of the rule storage 2 based on the selection information of the matched failure knowledge information and is executed on the service executor 11.