An operation management apparatus monitors the performance information of a system executing services and extracts correlation variants of the performance information, thus allowing the management to detect and localize performance-degrading faults of the system. It is determined whether or not the range of correlation collapse ascribed to the performance information falls within the normal range of correlation collapse measured in the normal operation of the system. A history is retained with regard to the range of correlation collapse ascribed to the performance information which does not fall within the normal range of correlation collapse. It is determined whether or not the history accumulating the predetermined number of ranges of correlation collapse approximates to the fault range of correlation collapse measured in the faulty operation of the system, thus discriminating a fault model on the basis of the performance information.