Provided is an inputting device that is disposed in an opening of a cabinet surface. The device includes an elastic sheet having an outside surface disposed on an inside surface of the cabinet including the opening and across the opening. A sliding key is fixed on the outside surface of the elastic sheet with at least a portion in the opening of said cabinet surface. The device also includes sensors to detect movement, in a horizontal direction that is substantially parallel to said cabinet surface, of the sliding key. The device also includes guides being possible to be recognized optically that are disposed on designated positions on the elastic sheet, and the sensors detect the moved direction and the amount of the horizontal movement of the sliding key by reading the movements of said guides optically.