To accurately work a lens fitting hole of a revolver of an assembled state.

The revolver to which an outer wheel forming plural holes to be tapped of screws to be screwed into an objective on the same circumference, an inner ring supported by the outer ring so as to relatively rotate and a click member spread over the outer ring and the inner ring and mutually engaged with both the rings to position and fix the outer ring on the inner ring are assembled is positioned and held on a working device 1 for cutting a screw thread into the holes to be tapped. The positioning and holding device is provided with an inner ring fixing means for positioning and fixing the revolver 4 of the assembled state on a fixed position by engaging the inner ring, an outer ring rotating means 12 for rotating the outer ring in the fixed state of the revolver 4 by the inner ring fixing means, a rotation control means 14 for detecting whether the click member is engaged or not and stopping the drive of the rotation means 12 at the time of detecting the engagement of the click member, and a clip means 13 for holding the outer ring and the inner wheel prior to the threading into the holes to be tapped, locking the relative rotation of the outer ring with the inner ring and releasing the holding after cutting the screw thread.