JIG FOR MACHINING TUBE

PURPOSE:To securely support the inner circumferential surface and the outer circumferential surface of a tube in a short time and easily so as to be turnable. CONSTITUTION:A jig for machining tube comprises a stator 11, and a rotor 12 that has been rotatably supported by the stator 11 via bearings 13, 14. The rotor 12 comprises a rotor body 21, and a cylindrical driving member 22 that is slidable thereto. To the rotor body 21, a plurality of holding pins 24 that are inserted into a plurality of radial holes and movedly driven in the radial directions respectively so as to be engaged with a second taper surface 52 by the axial movement of the driving member 22 for holding the inner circumferential surface or the outer circumferential surface of the tube are provided. And also a driving screw 23 is provided, by the backward and forward movement thereof, whose end part is engaged with a first taper surface 51 for moving the driving part 22 in the axial direction.