Abstract: An eccentric rotation drive mechanism which is rotatably contained in a first slide container is provided with an outer cylinder, an internal cylinder which is housed at eccentric position thereof and a first air motor contained therein. One end of a rotation shaft portion, that is, a shaft of the first air motor is fastened to a hole making tool, the other end of which is coupled to the end surface of the outer cylinder through a first reduction device. The rotation of the air motor makes the hole making tool rotate and revolve and simultaneously the rotation of a second air motor mounted outside of a casing is transmitted to a ball screw through a rotation transmission device inside of a second slide container to advance and retreat a feed drive mechanism so as to machine a hole in a workpiece.