To provide an excellent cutting characteristic and an excellent cutting life by using a nitrogen diffusion layer, a carbon diffusion layer or a nitrogen/ carbon diffusion layer for the surface hardened layer of the tip of a steel based cutting tool, and changing the shape of a cutting edge.

A surface treatment is properly applied to a steel based tool material chamfered with a cutting edge face 11, i.e., a first layer which is a nitrogen diffusion layer, a carbon diffusion layer or a nitrogen/carbon diffusion layer is formed on a steel based matrix surface, and a second layer which is a hardened film layer made of one or more kinds of metals selected from a group of Al, Ti, Zr, Hf, V, Nb, Ta, Cr is formed on the first layer. A third layer which is a hard film layer made of TiAlN is formed on the second layer. The shape of the cutting edge face 11 is variously changed. An excellent cutting characteristic and an excellent cutting life can be obtained.