A head-mounted device including a main frame couplable to an electronic device and a support part configured to affix the main frame to a facial side of the user, and an auxiliary input device including a body, an input module disposed on at least one surface of the body and configured to process an input signal for controlling a function of the electronic device, a sensor module disposed in the body and configured to obtain sensing information in accordance with a movement of the auxiliary input device, and a connection part electrically connectable to the electronic device and configured to serve as a path through which the input signal and the sensing information are transmitted to the electronic device is provided.