To provide a prize contest system capable of increasing the accuracy of marketing information obtained from a prize contest by assuring the fairness of the prize contest and a commodity with storage medium usable in the prize contest system.

This prize contest system 1 mainly comprises a book 20 with an RFID tag 22, a server 3, a terminal at an agent 15, a terminal 7 at a dealer 17, and a terminal 9 at a prize contest announcement shop 19. After the success or defeat information and identification information are written in the RFID tag 22 by the basic information writing means 23 of the server 3, the book 20 is delivered. When a consumer purchases the book 20, the purchase completion information is written in the RFID tag 22 by the terminal 5 at the dealer 15. By the terminal 9 at the prize contest announcement shop 19, information in the RFID tag 22 is read and, only when the purchase completion information is discriminated to be present, the success or defeat information is discriminated. Thus if a person obtains the book 20 by an unfair method, the person cannot participate in the prize contest.