PURPOSE: To efficiently execute reproducing work of a used rail by automatically positioning the used rail on a machine and free-cutting the head part of the rail and both of its corner parts to modificate.

CONSTITUTION: A rail 11 mounted on a horizontal surface plate 18 and automatically centered by a horizontally pushing device 31 is grasp-fixed by a clamp piece 41. Next, in parallel with detecting a deviation quantity by contacts 71 and 84, the head part of the rail 11 and both of its corner parts are freely cut through the use of a head part free-cutting cutter 50 and a corner free- cutting cutter. Thus, the free-cutting work of the rail is automated to facilitate the reproducing work of the used rail.