PURPOSE: To reduce stress concentration on the edge of a blade and avoid getting the edge nicked by grindingly forming a micro-rounding on edges of a first and a second blade and providing a bead on the top of the first blade.

CONSTITUTION: A hard metal part 11a of an upper blade 11 is rounded into a small size in an edge 13 by grinding similarly a hard metal part of the lower blade is rounded into a small size in an edge. The radius (r) of the micro- rounding is set to preferably 0.5 μm or 10 μm. A bead 14 of 0.1 mm or 1 mm is provided in the top of the upper blade 11. As a result, when a material web such as paper is cut or sheared longitudinally between the upper/lower blades, the stress is reduced from concentrating in the edges 13 of respective blades. This constitution can avoid the chip from being formed in the edge 13.