Effective utilization and maintenance of direct communication are provided.A state monitoring unit monitors a state of a predetermined number of terminal groups. Each terminal group includes a predetermined number of first communication terminals, and a second communication terminal that performs direct communication with the first communication terminals while being connected to a base station, When the state comes to fail to satisfy a certain condition, a group structure control unit changes a structure of the terminal groups. For example, the state monitoring unit monitors a communication traffic volume of data communication passing through the second communication terminal in each of the predetermined number of terminal groups. Also, for example, the state monitoring unit monitors a state (communication quality, remaining battery level, and the like) of the first communication terminal and/or the second communication terminal.