To improve the abrasion resistance of a cover layer and prevent the occurrence of damage and peeling by forming an outer layer with κ-type aluminum oxide, and providing a region where grains having the α-type crystal structure and grains having the κ-type crystal structure are mixed directly above an inner layer.

Cemented carbide is used as a base material, an inner layer and an outer layer are provided on the surface, and the inner layer is formed with two layers or more of Ti(CwBxNyOz), where w+x+y+z=1 and w, x, y, z≥0. The mixing ratio of α-type aluminum oxide grains and κ-type aluminum grains directly above the inner layer is preferably set to κ/α=1 to 4 to obtain the κ-type aluminum oxide layer on the outer layer. When the κ/α ratio is kept in this range, high degree of adhesion and the formation of the final κ-type crystal structure aluminum oxide layer can be easily reconciled. The mixed state of κ/α exists not only in the first line, and the κ/α ratio is decreased toward the upper layer and becomes zero in the film.