PURPOSE: To extend the plastically deformed part of a long columnar body into a spiral shape by pressing the working face of a caliber of eccentric ring roll against the column surface of a columnar body to plastically deform a part thereof and moving the caliber of ring roll in the intersecting direction with the body.

CONSTITUTION: Eccentric ring rolls 3, 5 serving also as the supporting devices of a pipe 7, are provided adjacently to an eccentric ring roll 4 to make the pipe 7 with a mandrel 6 inserted therein penetrate the calibers D1, D2, D3 of rolls 3, 4, 5 by a propelling device 14. At that time, when the rolls 3... and the calibers D1... are eccentrically rotated through the inner face of a gear 9 supported by a housing, after connecting the rolls 3 and 5 to each other through the ring roll 4 by a connecting rod 17 while maintaining the phase difference of about 180° between the rolls 3, 5 and the roll 4; a part plastically press-deformed by the caliber D2, advances while moving in the circumferential direction of pipe 7. Further, the caliber D2 is eccentrically rotated while push-advancing the pipe 7. In this way, the plastically deformed part of pipe is extended into a spiral shape.