PURPOSE: To obstruct such an unfair conduct as to increase the use frequency time data of a prepaid card, by subtracting use frequency time data from remaining frequency data contained in said prepaid card every time said prepaid card is used, and updating said remaining frequency data to the latest one.

CONSTITUTION: When an IC card 1 is inserted in a card machine 2 and it is confirmed by a comparator 21 that the remaining frequency value (A) is not less than 1, an AND circuit 22 outputs the value (A) to a discriminator 23 where the use frequency time data (B) supplied from a supply section 27 is subtracted from the value (A). If the result of the subtraction is over 1, a switch 25 is closed through an OR circuit 26, so that the supply section 27 is operated to offer a service to a user. Simultaneously, the data (B) is fed to the IC card 1 to be subtracted from the remaining value (A) by a subtractor 13 for updating. Accordingly, the latest remaining value is registered in a memory 11 every time of use. Even when some numerical data is added to an input terminal 14 for revising the remaining data in the IC card 1, the sabtractor 13 is so arranged as only perform the subtraction, thereby eliminating the change of practicing a dishonest action.