To maintain cutting performance over many hours by radiating frictional heat generated during cutting to suppress advancing of wear due to lowering of hardness of a cutting edge part, in a cutting blade.

A fin 4 is integrally mounted on a main body 2 constituting the cutting blade. The fin 4 is made of copper aluminum, gold, silver, zinc or alloys of them having excellent heat conductivity, . The frictional heat generated during cutting is radiated and a temperature rise of the cutting edge part 1 is suppressed to prevent softening. By maintaining wear resistance, an initial shape is maintained over many hours to suppress lowering of cutting performance.