In a mobile terminal device, a communication unit configured to communicate wirelessly in a first communication mode in which the mobile terminal device communicates with another mobile terminal device directly, or a second communication mode in which the mobile terminal device communicates with an external network via a router device. A communication control unit controls the operation of the communication unit. The communication control unit controls the switching of the first communication mode and the second communication mode in the communication unit and notifies the user that the first communication mode is terminated when the first communication mode is switched to the second communication mode.