Abstract: An interface unit includes an interface controller for controlling a bidirectional signal relative to an external host computer, a communication controller for controlling data communication with a noncontact IC card according to an output signal sent from the host computer, and a memory accessible by both the interface controller and communication controller. A noncontact IC card is very useful because of its accessibility at a remote place. A connector of the noncontact IC card can be protected from mechanical damage. With the interface unit, the noncontact IC card can be accessed as quickly as a contact IC card is.