The present invention provides a nonvolatile memory which includes a card controller, a reprogrammable nonvolatile memory and an IC card chip. The card controller is capable of outputting at least one of reset response information (ATR) outputted from the IC card chip in response to a reset instruction to the IC card chip and information indicative of an erase unit of a flash memory to the outside in response to a predetermined command supplied from outside. A card host is capable of causing the card controller to change an operating speed or operating frequency or the like of the IC card chip by reference to the ATR information. Upon reprogramming of memory information with respect to the reprogrammable nonvolatile memory, the card host is capable of sending write data equivalent to an amount commensurate with an erase unit to the nonvolatile memory by reference to the information indicative of the erase unit and giving write instructions.