A management computer stores, in a memory, virtual logical volume management information showing information on virtual logical volumes provided to a host computer by a storage device, and pool management information showing information related to a use status of pools. The management computer acquires performance information related to an access to the storage device from the host computer, determines whether the acquired performance related to the access satisfies a predetermined first required performance, or not, and specifies any virtual logical volume which is a cause of the state based on the virtual logical volume management information if the first required performance is not satisfied. The management computer calculates a capacity consumption trend of the real area included in each pool based on the pool management information, creates a countermeasure for satisfying the first required performance implementable after a given time, and outputs the countermeasure to an output device.