PURPOSE: To remove the residual stress of a cylinder without performing a heat treatment, by utilizing projecting streaks at both external circumference ends of a cylinder worked by spinning, and then applying a tensile force in an axial direction.

CONSTITUTION: Deformed bundling shafts 2 each consisting of a large-diameter part engaging the internal circumference of a cylinder 1 hermetically and a small diameter projecting an end surface of the large-diameter part are inserted into the cylinder 1 at both ends. A gripping ring 3 of two-split constitution which has an opening to engage the small diameter part in the center of the end plate and an internal flange 3a to engage a projecting streak at the internal circumference of the cylindrical part is engaged with each external circumferential end of the cylinder 1, and then fixed by engaging a fixing ring 4 with the gripping ring 3. The small diameter part of the shaft 2 is equipped with a retaining ring 5 for the gripping ring 3. For this purpose, the small diameter part of the shaft 2 is engaged with the output terminal of a load generating device and a tensile force is applied to remove residual strain.