PURPOSE: To make it difficult to copy the collation data stored in an IC card and to prevent the wrong use of the card.

CONSTITUTION: The IC card 2 contains a main memory 21, a 1st auxiliary memory 22a which previously stores the 1st collation data, a 2nd auxiliary memory 22b which previously stores the 2nd collation data, and a timer 23 which selects the memory 21 to attain the external reading/writing operations in a normal operation mode and also selecting successively the memories 22a and 22b to read out the 1st and 2nd collation data in a collation mode. In an IC card system 1, an access is permitted to the card 2 only when the coincidence is secured between both collation data. Therefore, an IC card having a single auxiliary memory is unable to correctly copy two types of collation data.