A mobile device having at least two antennas can circumvent transmission problems caused by a user's grasp of the device. A sensor unit is disposed at a specific location of a device body and creates a sensor signal by detecting the contact or proximity of a particular object such a user's hand. When receiving the sensor signal, a control unit selects one of the antennas depending on the sensor signal and establishes a communication path based on the selected antenna. The selected antenna involved in the communication path is typically relatively free from degradation in transmission caused by a user's grasp of the mobile device. The radiation property of the mobile device, which may be degraded due to a user's grasp, can exhibit relatively little or no degradation as compared to the typical degradation in performance when the mobile device is being grasped.