To reduce the temperature rise in a device housing, prevent reduction in stopping position accuracy by a change in a backlash, and eliminate the possibility of seizure or the like by interposing steel balls between respectively adjacent respective active racks, and forming them so as to respectively perform rolling motion of point contact.

In a device housing 7, eccentric three swinging type active racks 12A to 12C are connected to respective eccentric racks 15A, and by rotation of this shaft 15A, the respective active racks 12A to 12C move on an active rack 11 of a cycloid tooth shape (a rack tooth) T1 while vertically moving by having a phase difference of 120°, and respective ones of the respective active racks 12A to 12C advance while generating thrust in order. Since the mutual respective active racks 12A to 12C relatively perform rolling motion in point contact by respective steel balls B, heating is reduced, and a temperature rise in the device housing 7 is restrained. Therefore, positioning stopping accuracy is maintained, and seizure or the like of respective parts can be prevented.