PURPOSE: To always maintain a constant clearance and reduce the manhour for the adjustment of clearance by installing an elastic body for always urging the cutting-edge block of a movable knife edge towards a pad side part, between a holder and the block.

CONSTITUTION: The slidable part 33 and the cutting edge part 16 of a cutting- edge block 19 are slided downward by the lowering of a movable knife edge 15, and the edge part of a workpiece W is shearing-worked by a punch 3. Though the slidable part 33 and the cutting-edge part 16 of the cutting-edge block 19 are worn, they are always urged towards a pad 9 side by an elastic body 23, and a proper clearance (t) is always maintained. Therefore, the waste of a large amount of manhour for the adjustment of the clearance (t) can be avoided.