To repeatedly perform a coupon service by providing a card reader- writer capable of reloading information on the information recording part and reversible display part of a card.

An article code, discount information and a personal identification code recorded on an information recording part 3 of a card 2 are read by a card reading and reloading means 8 inside a card reader-writer 5. An article code indication 12 on a tag 11 of an article 10 scheduled to be purchased is read by an article code reading part 7. The selling amount data of the article are sent from a database 13a, the discount information is sent from the card reader-writer 5 to a data control means 18, and a price amount subtracting a discount amount from the amount data is calculated. The article price is printed out on a receipt by a printout part 16. In accordance with the contents of a used coupon, the article and discount information on the information recording part 3 and a reversible display part 4 of the card is reloaded and the card 2 is ejected from the card reader-writer 5 and returned to a customer.