PURPOSE: To automatically adjust the positional adjustment of a stopper member with accuracy and speed in the cut length setting device of a cutter.

CONSTITUTION: The origin of a stopper member 21 is determined at the position a certain fixed distance away from the cutting face 1a of a shear die 1 by setting the amount of the thickness of a cutter 8 at a certain fixed length. Because the stopper member 21 is automatically stopped at the position a predetermined distance away from the origin, the cut length of wire rod can be adjusted to a set length with accuracy and speed, resulting in eliminating the need for worker to manually adjust the cut length and automatically adjusting with accuracy and speed and also realizing the situation suitable for automatic operation of a header.