To provide a composite sintered body cutting tool reducing the use amount of tungsten and comprising a TiCN-based cermet excellent in peeling resistance and thermal crack resistance, and WC-based hard metal.SOLUTION: In a composite sintered body cutting tool comprising a TiCN-based cermet and a WC-based hard metal, at least a part of surface of the periphery including a cutting edge is configured by the WC-based hard metal layer (having the thickness of 0.03 to 0.3 time that of the tool). Besides, an interface layer having an average layer thickness of 5-200 μm is formed to the side of the WC-based hard metal layer from the interface of that hard metal layer and the TiCN-based cermet, and the interface layer is configured by the WC particles having 5-50 area% and a mixed phase having 50-95 area%. The total content of W and Mo existing in the mixed phase is 0.8 to 1.2 time (by atomic ratio) that of Co and Ni in the mixed phase, and the TiCN-based cermet is configured by at least one layer of that cermet.SELECTED DRAWING: Figure 1
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