To maintain operating sense, using a low load to a piezoelectric actuator.

When driving a control wheel pinion 77 and a control wheel from a previous rotation holding position to the present rotation holding position, they are driven by a piezoelectric actuator 71 until reaching a predetermined drive switching position, and driven by an energizing force in the rotating direction of a positioning jumper 300 after reaching the drive switching position. Then, the control wheel driven to the present rotation holding position is held in that position by the energizing force in the radial direction of the positioning jumper 300.