PURPOSE: To increase the security performance of the IC card by limiting the range of access to the memory on the IC card.

CONSTITUTION: The CPU is provided with at least one of a program segment register(PSR) where a value can be set only once after resetting, a normal program counter(PCI) which indicates the address of an execution instruction of a program, and a register(DRI) for accessing data on the memory, and an execution or read/write address is found through the operation of the program segment register(PSR) and program counter(PCI) or program segment register(PSR) and register (DR) to limit access to the memory.