Abstract: A possible fraud action in game-Item exchange can be prevented. When proposing item exchange from Taro to Hanako, Taro does not force Hanako to “exchange for the specified game item.” Instead, the “value information” of Taro's game item in a game is described in an exchange proposal message sent to Hanako. Hanako can see the message and can refer to the “value information”, and select by her own initiative a game item to be presented for the exchange from the game items possessed by her. When Hanako accesses Hanako's game information with a Hanako terminal and an “item management screen” is displayed on a Hanako terminal display, a button indicating “you have an exchange proposal message, see the details” is displayed. Hanako selects one or more game items from a displayed list. Hanako clicks on a button to “send an exchange accepting message” in an “item exchange screen.