PURPOSE: To correspond to the expansion and change of an IC card by storing a main control procedure to exchange information at the section of external equipment at a first storing means beforehand, and storing a sub-control procedure for a main control means at a second storing means which can freely rewrite.

CONSTITUTION: By only storing a discriminating procedures of the writing instruction and executing the instruction of a sub-routine into the main program of a ROM 2, a sub-routine program is stored into a EEPROM 22, therefore, an expansion program in respect to the main program can be externally inputted and executed as the sub-routine program. Further, the contents of the EEPROM 22 can be freely rewritten. Thus, plural expansion programs are made unnecessary, and the memory of the IC card can be economized. Since the main program is stored in the ROM, the storage contents cannot be rewritten, and the main program can be prevented from changing and abusing.