An input device including: an input unit having a plurality of buttons disposed in a handle of a vehicle; an interface unit configured to receive data concerning the vehicle or to transmit an input signal received via the input unit to an external device; a processor configured to change a function of at least one of the plurality of buttons to a set function based on a manipulation signal from the input unit; and a display configured to display an image corresponding to the set function of the at least one of the plurality of buttons.