A vibration-side housing is attached to a tip of a handle-side housing, and a motor in which a plate cam is attached to a rotating shaft is housed. A vibration tube mounting opening opens at distal end part of the vibration-side housing, and a vibration tube is mounted thereon. The vibration tube is provided to vibrate in a forward-backward direction while urged in the plate cam direction via a spring with respect to the vibration-side housing. The vibration tube contacts with the plate cam via a roller at a rear end part. A reamer mounting opening opens at a tip of the vibration tube, and receives and tightly holds an insertion part of the reamer. The reamer including the bendable needle part is attachable/detachable to the vibration-side housing.
