A storage system comprising: a first storage device and a second storage device controlled by a control circuit; first power control means (204, 114) configured to perform power control corresponding to a storage device of a first type whose lifetime is influenced by a number of shifts to a power saving state; second power control means (202a, 202b) configured to perform power control different to the power control by the first power control means and corresponding to a storage device of a second type whose lifetime is less influenced by a number of shifts to the power saving state than the storage device of the first type; and control means configured to discriminate whether each of the storage devices, among the first and second storage device, is of the first type or the second type, and controlling the storage devices, wherein the control means is configured to determine the storage device that is the access destination for an access request and, wherein the control means, upon receiving from the control circuit a shift instruction that is for causing the storage devices to shift to the power saving state and that does not distinguish the type of the storage devices, is further configured to, after processing with respect to the storage device that is not the access destination of the access request based on a previous access request completes, to instruct power control means corresponding to the storage device that is not the access destination of the access request to perform power control for causing said storage device to shift to the power saving state, when a predetermined amount of time in which a new access request does not occur elapses after processing based on the previous access request completes, wherein the predetermined amount of time is smaller if said storage device is discriminated as the second type than if said storage device is discriminated as the first type. a first storage device and a second storage device controlled by a control circuit; first power control means (204, 114) configured to perform power control corresponding to a storage device of a first type whose lifetime is influenced by a number of shifts to a power saving state; second power control means (202a, 202b) configured to perform power control different to the power control by the first power control means and corresponding to a storage device of a second type whose lifetime is less influenced by a number of shifts to the power saving state than the storage device of the first type; and control means configured to discriminate whether each of the storage devices, among the first and second storage device, is of the first type or the second type, and controlling the storage devices, wherein the control means is configured to determine the storage device that is the access destination for an access request and, wherein the control means, upon receiving from the control circuit a shift instruction that is for causing the storage devices to shift to the power saving state and that does not distinguish the type of the storage devices, is further configured to, after processing with respect to the storage device that is not the access destination of the access request based on a previous access request completes, to instruct power control means corresponding to the storage device that is not the access destination of the access request to perform power control for causing said storage device to shift to the power saving state, when a predetermined amount of time in which a new access request does not occur elapses after processing based on the previous access request completes, wherein the predetermined amount of time is smaller if said storage device is discriminated as the second type than if said storage device is discriminated as the first type.