With a simple configuration, a area in which an operating unit can move is prevented from being limited. Provided is an operation input device including a display; an operating unit that operates a display object displayed on the display; a head-mounted unit that is mounted on the head of an operator; relative position sensors that detect a relative position and a relative orientation of one of the head-mounted unit and the operating unit with respect to the other; and a control unit that actuates the display object displayed on the display on the basis of changes in the relative position and the relative orientation detected by the relative position sensors.