To produce a cemented carbide excellent in smoothness, in which the discharge property of chips is improved by reducing the friction between the sintered surface of a cutting tool and the chips and also the adhesion and seizure between the sintered surface and the chips are prevented and resultantly tool life is improved, a coated cemented carbide, and to provide a manufacturing method of them.

In the cemented carbide excellent in smoothness, at least a part of the surface of the cemented carbide containing a hard phase composed essentially of tungsten carbide and a binding phase composed essentially of iron group metal has a sintered surface. Further, when Ds represents the average grain diameter of the hard phase existing in the sintered surface and Di represents the average grain diameter of the hard phase existing in the inner part of the cemented carbide, Ds≤Di is satisfied.