To provide a system by which an advertisement effect is improved by presenting a participation type game so as to make a user positively watch an advertisement page concerning an advertisement on the Internet and by which rational cost setting is enabled corresponding to the advertisement effect by automatically changing the advertisement cost or kinds/amounts of prize gifts corresponding to the number of persons watching the advertisement.

Concerning this prize system for advertisement, a game whose result is revealed later is presented on the web together with the advertisement, participation in betting to this game is called for to a user registered beforehand, a prize provided corresponding to the result of the game, and the advertisement cost of an advertiser and the total amount of prizes are automatically calculated corresponding to the number of these participants. The game is composed of the selections of a plurality of answers to a question and the final winner of the prize is determined out of the winners of the game by drawing lots.