1. A storage controller comprising a plurality of control sections including storage sections into which data transmitted from a host unit is cached, one of the control sections being a main control section which controls firmware update in the control sections, the main control section having: an instruction updater sending an update instruction to a sub control section in the control sections in which firmware is to be updated; and an area instructor requesting the sub control section to transmit area information indicating the location of a cache area in the storage section in which a cache is held after the completion of updating of the firmware in the sub control section, and providing an instruction to set the location of the cache area on the basis of the transmitted area information, the sub control section having: an area information obtainer obtaining, according to the instruction from the an area instructor, area information indicating the location of the cache area in the storage section; an area information transmitter transmitting to the an area instructor the area information obtained by the an area information obtainer; and an area setter setting the location of the cache area in the storage section on the basis of the instruction from the an area instructor.