PURPOSE: To provide the composite material made of polycrystalline diamond and the cemented carbide with reduced adhesion of the resin by constituting the surface layer part of the prescribed thickness containing the diamond of the prescribed amount, and the inside made of the WC base cemented carbide or TiC base cermet of the prescribed hardness.

CONSTITUTION: A composite material of double structure made of polycrystalline diamond and the cemented carbide where the surface is made of the hard and corrosion resistant polycrystalline diamond and the inside is made of the cemented carbide or cermet rich in the toughness. The surface layer part is of the thickness of 50-5000μm and has the composition consisting of, by volume, 100-60% diamond, 0-40% TiN, 0-20% AIN, and the binder having the composition consisting of 0-40% Co, 0-40% Ni, or 0-20% Al and 0-10% Cr as a part of alternative. The inside is made of the WC base cemented carbide or TiC or TiCN base cement whose hardness is ≤HRA93. This constitution reduce the adhesion of the resin on the composite material, improves the breaking resistance and the fracture toughness, and improves the reliability and the service life.