A return is reliably executed to a player who has paid a predetermined amount to a game machine. The timing of this return is determined by lottery, and its result is displayed on the game machine. This thrills the player with expectation of the return, thereby keeping the player long on the same game machine. As the result, it is avoidable that the player waiting for a prize for a long time loses enthusiasm for the game and keeps away from the hall (i.e., a reduction in the number of customers).