In this diamond-coated cemented carbide cutting tool, (1) an average particle size of WC particles is 0.5 to 0.9 μm, (2) (Rz) being 0.5 to 1.0 μm, a maximum distance between the concave and convex (Δ) is 0.5 to 1.5 μm, a length (Ye) is 0.5 to 2.0 μm, (3) a sum of areas of WC particles, which satisfies (L1) being 0.4 to 0.8 μm, (L2) being 0.2 to 0.4 μm, and (L1)/(L2) being 1.5 to 2.5, is 70 area % or more, (4) an average grain size of diamond crystals in a region of 0.5 to 1.5 μm from the body interface is 0.1 to 0.3 μm, and (5) columnar crystals satisfying at least one of: a ratio of crystals, which has a growth direction shifted in 10 degrees or less from the diamond film thickness direction, being 90% or more; or an orientation ratio of being 30 to 70%.