To reduce the load on a host computer and the using quantity of a communication line, and to speedily process transaction permission.

An IC card 10 is constituted to send data mutually with a terminal equipment. In this case, the IC card 10 adds an accumulated amount concerning transaction previously stored in EEPROM 13, etc., and a transaction amount which a user has input from the terminal equipment in a present transaction, and additionally judges whether the adding result exceeds a credit limit amount included in a credit parameter. Namely, the IC card 10 executes credit inspection concerning the present transaction. Then, at the time exceeding the credit limit amount, the IC card 10 outputs a transaction rejecting code to the terminal equipment. The terminal receiving this transaction rejecting code disables the using of the IC card 10.