PURPOSE: To allow the title IC card to have generality, and also, to constitute it so that data of a large capacity can be stored by providing a compressing means of the data and a data expanding means for expanding the compressed data.

CONSTITUTION: Data which is supplied to a signal connecting mechanism is inputted to a data compressing/expanding circuit 15 under the control of a CPU 12, subjected to a compression processing of the data therein, and thereafter, stored in a memory 13. The compressed data read out of the memory 13 is inputted to the data compressing/expanding circuit 15, and brought to expansion processing therein. Data whose read-out has been requested from the outside among the data which is returned to the original state by the data compressing/expanding circuit 15 is supplied to the signal connecting mechanism 14 through the CPU 12, and sent out to an IC card reader/writer device therefrom.