A game server device, which can communicate with a plurality of game terminal devices through which registered players can play a competitive game, is provided with a rating calculation unit for calculating ratings of players for each competition; a comparison unit for comparing a mean value of ratings of all registered players and a predetermined reference value; an adjustment unit for carrying out processing to bring the means value closer to the reference value; a CPU player setting unit for setting a CPU player to an opponent player of the registered player. When the average value is smaller than the reference value, the adjustment unit sets the CPU player as an opponent player of the registered player, and sets the rating of the CPU player to be larger than its original rating of the registered player, whereas in the reverse case, the adjustment unit sets the rating of the CPU player to be smaller than the original rating in the calculation of the rating of the registered player. The mean value of all players' ratings indicating their strength in the competitive game is brought closer to the reference value.