In a communication system capable of executing terminal-to-terminal communication in which wireless communication is performed directly without an intervention of a base station device between a first terminal device that is in a state in which cellular communication with the base station device can be executed and a second terminal device that is not in the state in which cellular communication with the base station device can be executed, the base station device generates control information necessary for the first terminal device to search for the second terminal device, and transmits the generated control information to the first terminal device.