In order to protect the user security data, provided is a memory card capable of preventing the data leakage to a third party not having the access authority by imposing the limitation on the number of password authentications and automatically erasing the data. In a system comprised of a multimedia card and a host machine electrically connected to the multimedia card and controlling the operations of the multimedia card, a retry counter for storing the number of password authentication failures is provided and the upper limit of the number of failures is registered in a register. When passwords are repeatedly entered once, twice, . . . and n times and the retry counter which counts the entries reaches the upper limit of the number of failures, the data is automatically erased so as not to leave the data in the flash memory.