A surface-coated cutting tool comprising: a hard substrate; a lower layer which is formed on a surface of the hard substrate, consisting of a Ti and Al composite nitride layer having a variable composition structure and an average thickness of 1.5 to 10 μm; and an upper layer having an average thickness of 1 to 10 μm, which is formed on the lower layer and having a texture in which fine grains of crystalline Ti (C,N) based compounds or fine grains of crystalline (Ti, Al)(C, N) based compounds are dispersively distributed in a matrix of a carbon based amorphous material containing W, wherein the variable composition structure of the lower layer has a composition distribution structure in which: portions of maximum Al content and portions of maximum Ti content exist alternately with a predetermined interval in a thickness direction of the Ti and Al composite nitride layer; Al and Ti content change continuously from the portion of maximum Ti content to the portion maximum Al content, and from the portion of maximum Al content to the portion of maximum Ti content; each of the portions of maximum Al content satisfies a compositional formula: (Al 1-X Ti X)N, where X ranges from 0.05 to 0.35 by atomic ratio; each of the portion of maximum Ti content satisfies a compositional formula: (Ti 1-X Al X)N, where X ranges from 0.05 to 0.35 by atomic ratio; and the interval between a portion of maximum Al content and an adjacent portion of maximum Ti content is 0.01 to 0.1 μm, and wherein the upper layer contains, W: 5 to 40 atomic %, Ti: 0.5 to 30 atomic %, nitrogen: 0.5 to 30 atomic %, and a balance consisting of carbon and unavoidable impurities, or the upper layer contains, W: 5 to 20 atomic %, Ti: 2.5 to 10 atomic %, nitrogen: 0.4 to 22.5 atomic %, Al: 1.6 to 15 atomic %, and a balance consisting of carbon and unavoidable impurities. a hard substrate; a lower layer which is formed on a surface of the hard substrate, consisting of a Ti and Al composite nitride layer having a variable composition structure and an average thickness of 1.5 to 10 μm; and an upper layer having an average thickness of 1 to 10 μm, which is formed on the lower layer and having a texture in which fine grains of crystalline Ti (C,N) based compounds or fine grains of crystalline (Ti, Al)(C, N) based compounds are dispersively distributed in a matrix of a carbon based amorphous material containing W, wherein the variable composition structure of the lower layer has a composition distribution structure in which: portions of maximum Al content and portions of maximum Ti content exist alternately with a predetermined interval in a thickness direction of the Ti and Al composite nitride layer; Al and Ti content change continuously from the portion of maximum Ti content to the portion maximum Al content, and from the portion of maximum Al content to the portion of maximum Ti content; each of the portions of maximum Al content satisfies a compositional formula: (Al 1-X Ti X)N, where X ranges from 0.05 to 0.35 by atomic ratio; each of the portion of maximum Ti content satisfies a compositional formula: (Ti 1-X Al X)N, where X ranges from 0.05 to 0.35 by atomic ratio; and the interval between a portion of maximum Al content and an adjacent portion of maximum Ti content is 0.01 to 0.1 μm, and wherein the upper layer contains, W: 5 to 40 atomic %, Ti: 0.5 to 30 atomic %, nitrogen: 0.5 to 30 atomic %, and a balance consisting of carbon and unavoidable impurities, or the upper layer contains, W: 5 to 20 atomic %, Ti: 2.5 to 10 atomic %, nitrogen: 0.4 to 22.5 atomic %, Al: 1.6 to 15 atomic %, and a balance consisting of carbon and unavoidable impurities. portions of maximum Al content and portions of maximum Ti content exist alternately with a predetermined interval in a thickness direction of the Ti and Al composite nitride layer; Al and Ti content change continuously from the portion of maximum Ti content to the portion maximum Al content, and from the portion of maximum Al content to the portion of maximum Ti content; each of the portions of maximum Al content satisfies a compositional formula: (Al 1-X Ti X)N, where X ranges from 0.05 to 0.35 by atomic ratio; each of the portion of maximum Ti content satisfies a compositional formula: (Ti 1-X Al X)N, where X ranges from 0.05 to 0.35 by atomic ratio; and the interval between a portion of maximum Al content and an adjacent portion of maximum Ti content is 0.01 to 0.1 μm, and wherein the upper layer contains, W: 5 to 40 atomic %, Ti: 0.5 to 30 atomic %, nitrogen: 0.5 to 30 atomic %, and a balance consisting of carbon and unavoidable impurities, or the upper layer contains, W: 5 to 20 atomic %, Ti: 2.5 to 10 atomic %, nitrogen: 0.4 to 22.5 atomic %, Al: 1.6 to 15 atomic %, and a balance consisting of carbon and unavoidable impurities.