SURFACE-COATED TOOL

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A surface-coated tool which comprises a base and, superposed on the surface thereof, two coating layers represented by the following general formula (1). The first coating layer of those coating layers, which is the layer overlying the base surface, has a layer thickness of 0.1-1 µm and is constituted of granular crystals having an average crystal diameter of 0.01-0.1 µm. The second coating layer of those coating layers, which is the layer overlying the surface of the first coating layer, has a layer thickness of 0.5-5 µm and is constituted of columnar crystals which have grown in the direction perpendicular to the base. The columnar crystals have an average crystal width, as measured in a direction parallel to the base, of 0.05- 0.3 µm. The average crystal width of the second coating layer is larger than the average crystal diameter of the first coating layer. M1-aAla(CbN1-b) (In the formula (1), M represents at least one metallic element selected among the elements in Groups 4, 5, and 6 of the Periodic Table, silicon, and the rare earth elements; a satisfies the relationship 0.25≤a≤0.75; and b satisfies the relationship 0≤b≤1.)