An IC card transmits data received from a card reading and writing apparatus to a portable terminal via an external interface without changing the received data, or after the received data is converted according to an appropriate conversion scheme or is converted into other packet data. Conversely, the IC card transmits data received from the portable terminal via the external interface to the card reading and writing apparatus via a non-contact interface without changing the received data, or after the received data is converted according to an appropriate conversion scheme or is converted into other packet data. Therefore, non-contact data communication can be performed between the information processing terminal connected to the IC card and the card reading and writing apparatus.