A network game system is known which comprises a first game machine and a second game machine which are connected to a communication network, and in which the first game machine displays a game screen of a content corresponding to an operation executed in the first game machine and makes the second game machine display a game screen of a content corresponding to an operation executed in the second game machine by exchanging data with the second game machine via the communication network. As such a network game system, for example, a system is known which realizes a match of a soccer game by players of the first and second game machines.    [Patent Document 1] Japanese Patent Laid-Open Publication No. 2004-350910