Provided is a social game capable of, when a new group is created, allowing such a group to progress a game smoothly. A server device that provides a game, in which a plurality of players can participate, is connected to terminal devices operated by the players via a communication line, and comprises: an information storage unit; and a control unit. The information storage unit stores information on a first group, in which the players participate, and information on a second group, in which the players are supposed to participate; the control unit receives notification on acceptance of participation in the second group from the terminal devices, and when it is determined that the number of players in the second group reaches a certain number, stores the second group as a new first group at the information storage unit.