A storage tiered that satisfies desired performance is configured by recognizing the type and capacity of storage media of a storage apparatus, which are held by a user, and using the storage media.When adding a specified area of storage media to a storage tiered in response to a request from a host computer, a management computer: obtains storage media information, including I/O frequency of a data storage area of a volume(s) as well as performance information and structure information of the storage media, from the storage apparatus; identifies one or more storage media, which have not been allocated to any of the volumes with the I/O performance in excess of the I/O frequency, on the basis of the structure information of the storage media so that the data storage area of the volume(s), to which a specified storage in the storage tiered is allocated, would achieve a specified I/O performance target; and issues an instruction to the storage apparatus to create a storage tiered by using the identified storage media.