A storage system 1000 providing a storage area to an external device 1500 comprises a plurality of storage apparatuses 1100, 1200 and 1300 of different performance capabilities, and a storage controller 2600. The storage controller 2600 holds storage cost coefficients 3202 of the respective storage apparatuses 1100, 1200 and 1300, user cost allocation information 3302 for each user using the storage system 1000 from the external device 1500, and user cost distribution information 3402 that defines, for each user, proportions of an available space amount distributed to the storage apparatuses 1100, 1200 and 1300. The storage controller 2600 calculates an ideal utilization 3502 for each user, from the storage cost coefficients 3202 and the user cost distribution information 3402, and allocates, for each user, the ideal utilization 3502 to each of the storage apparatuses 1100, 1200 and 1300, in the order of the performance capabilities from highest to lowest.