A mobile device 1 has a USB transmitter-receiver 3 having one or more interfaces formed by one or more endpoints for exchanging information via the USB, one or more logical devices 61 to 65 performing the exchanging of information with a host computer 2 via the USB transmitter-receiver, and a controller 4 which, when a function of one or more logical devices is used, selectsas many interfaces as required for the exchange of information between the logical device and the host computer2 from the one or more interfaces within the USB transmitter-receiver.