A correlation model is updated quickly in the case that monitored metrics are changed.The correlation model storing unit 112 stores a first correlation model including a correlation detected for a pair of metrics in first plural metrics. The correlation model updating unit 103, in the case that a metric is added, judges existence of a correlation for each of pairs of metrics obtained by excluding the pair of metrics in first plural metrics from pairs of metrics in second plural metrics including the added metric and the first plural metrics, and generates a second correlation model by adding the detected correlation to the first correlation model.