PURPOSE: To prevent the occurrence of a strip-shaped trace by means of the straightening action of a plate-shaped straightening part by providing a torsion element in which right-hand torsion elements and left-hand torsion elements are axially and alternatively arranged with the end parts of the adjacent elements crossing each other and which is placed at least at the axial end part with a plate-shaped straightening part to which the end edge is extended.

CONSTITUTION: Right-hand torsion elements 1 and left-hand torsion elements are axially and alternatively arranged in series with the end parts of the adjacent elements crossing each other at a connecting angle of 90°C. In addition to this basic structure, the right-hand torsion element 1 positioned at the axial end part (one example only), together with a torsion body 11, is provided with a plate-shaped straightening part 12 to which the end edge is extended. The plate-shaped straightening part 12 has an axial length (l) and a width (d) which are mutually almost same and the part 12 has the same wall thickness as that of the torsion body 11, provided that, in the axial end part of the plate-shape straightening part 12, the wall thickness is made thinner gradually toward the end edge and uniformly from both surface side over the full range of width and in the state of being pointed linearly in the axial direction over the full range of width.