Surface-coated cutting tool

A surface coated cutting tool comprising a substrate and a coating layer on the substrate, the substrate comprising a WC-based cemented carbide comprising a hard phase component of WC grains and a binder phase primarily composed of Co, wherein

• (a) an interfacial layer is disposed between the substrate and the coating layer;
• (b) the interfacial layer includes a region A that has a W content WA and a C content CA directly above the hard phase component and a region B that has a W content WB and a C content CB directly above the binder phase, and the interfacial layer has an average thickness;
• at the midpoint across the average thickness of the interfacial layer, the W content WA in the region A is in the range of 90 to 99 mass %, while the W content WB in the region B is in the range of 30 to 65 mass %,
• the C content CA in the region A satisfies the expression:
• CA≤0.05 mass %, and
• the C content CB in the region B satisfies the expression:
• CA≤CB≤0.09 mass %.