A movable operation unit is movable on a two-dimensional operation surface of a main body. The two-dimensional operation surface is defined by an X-axis and a Y-axis perpendicular to each other. A Y-axis movable portion is rotatable around a rotation axis. The Y-axis movable portion is movable in the Y-axis direction when rotating around the rotation axis. The rotation axis extends in the X-axis direction relative to the main body. The Y-axis movable portion includes a sliding rail portion on which the movable operation unit is slidable in the X-axis direction. The movable operation unit is operable to slide in the X axial direction and move in the Y axial direction accompanied with rotation of the Y-axis movable portion around the rotation axis to performs a parallel shift in the two dimensional direction while regularly and constantly maintaining a posture of the movable operation unit.