In a game system using real operation objects, a decrease in real operation objects is detected. The quantity of real operation objects used repeatedly by being circulated is detected, the excess or shortage of the quantity is judged, and the judgment result is output. For example, in a ball throwing game, balls are used circulated by repeatedly supply and collection of balls. The quantity of circulated balls is detected, and, when the quantity is less than a specified threshold, whether or not a sufficient quantity of balls is supplied to a player is reported to a game system manager by, for example, outputting an alarm message. A player playing with insufficient balls is substantially given an increased difficulty level in game, that is, unfairness.