Abstract: A device for positioning the backward stroke end of a shearing blade for use in a bolt forming header comprises a shearing slide reciprocably mounted within a box-shaped frame and having a shearing blade attached to the leading end thereof and a first abutment member fixedly secured to the rear end thereof, said abutment member having an inclined face formed in the rearmost end thereof, a stopper member movably mounted on the rear end portion of said frame and having an inclined face formed in the portion thereof opposite to the inclined face of said abutment member, and an adjusting mechanism mounted on said frame for moving said stopper member in the direction perpendicular to that of reciprocation of said shearing slide, thereby adjusting the backward stroke end of said shearing blade.