A storage controller of the present invention enables a larger number of storage devices to be mounted while keeping the installation size small. A plurality of sub-storage units are disposed inside a high density-type storage unit. The respective sub-storage units comprise a plurality of hard disk drives, controller, memory, power supply device, and display part. The respective sub-storage units operate independently of one another. A controller creates a management table based on management data acquired from the respective sub-storage units. The user is notified when there is an error in the table contents. A display part lights up in accordance with an indication from a storage unit specification part, notifying the user of the location of the sub-storage unit.