A system for authenticating a memory card including: a capacity switching-type memory card host device including a capacity switch notification module which notifies a memory card targeted for exchanging information that the capacity switching-type memory card host device handles a capacity switching-type memory card, and a capacity switch authentication module which authenticates whether the targeted memory card is the capacity switching-type memory card; a capacity switching-type memory card including a capacity switching-type controller which flags the large-capacity expression register use flag on receipt of notification of being the capacity switching-type memory card host device; and a bus which transmits and receives data between the capacity switching-type memory card host device and the capacity switching-type memory card.