A memory card capable of connecting to a host device includes a flash memory, a host interface unit which transfers data between a host device and the memory card, and a transfer mode control unit which changes a data transfer mode based on a command from the host device. The transfer mode control unit outputs status data containing an error code to the host device if a transfer mode change command is inputted from the host device, instructing the memory card to change to a transfer mode not supported by the host interface unit of the memory card.