PURPOSE: To prevent negative shearing for preventing chipping in intermittent cutting operation, by providing a soft metal layer mounted integrally on a material to be cut on the side toward which the tool progresses.

CONSTITUTION: A soft metal layer 13 is mounted integrally on a material to be cut 12 on the side toward which a cutting tool 11 progresses by pressing it with a bypass or any other suitable way. The soft metal layer 13 has such hardness that is prevents the cutter blade from being caused to pitch by a force generated in negative shearing when the cutting blade of the tool 11 reaches the boundary of the material to be cut 12. Cutting operation is carried out in this state. By this constitution, the cutting tool can be effectively prevented from chipping.