PURPOSE: To secure the identification of an individual and to prevent an IC card from being used by a third person by storing the autograph signature of a user in the IC card and collating it with a signature at the time of transaction.

CONSTITUTION: The signature written by the user himself of the IC card 1 is stored in the IC card 1 as image data. At the time of transaction, image data stored in the IC card 1 is read, and the signature is obtained from the image data, whereby the signature and the signature 4 at the time of transaction are collated. If the coincidence of the signatures is recognized by the collation, transaction is executed, and in case of discrepancy, transaction is not executed. Thus, the IC card is prevented from unauthorized use by the third person.