Cutting tool

A cutting tool comprising a substrate and a hard layer provided on the substrate, wherein

• the hard layer includes a first unit layer and a second unit layer,
• one or a plurality of the first unit layers and one or a plurality of the second unit layers are alternately layered in the hard layer,
• a thickness of each of the one or plurality of first unit layers is 2 nm or more and 100 nm or less,
• a thickness of each of the one or plurality of second unit layers is 2 nm or more and 100 nm or less,
• the first unit layer is composed of a compound represented by TiaAlbBcN,
• the second unit layer is composed of a compound represented by TidAleBfN,
• an atomic ratio a of a titanium element in the TiaAlbBcN is 0.25 or more and less than 0.45,
• an atomic ratio b of an aluminum element in the TiaAlbBcN is 0.55 or more and less than 0.75,
• an atomic ratio c of a boron element in the TiaAlbBcN is more than 0 and 0.1 or less,
• a total of the atomic ratio a, the atomic ratio b, and the atomic ratio c is 1,
• an atomic ratio d of a titanium element in the TidAleBfN is 0.35 or more and less than 0.55,
• an atomic ratio e of an aluminum element in the TidAleBfN is 0.45 or more and less than 0.65,
• an atomic ratio f of a boron element in the TidAleBfN is more than 0 and 0.1 or less,
• a total of the atomic ratio d, the atomic ratio e, and the atomic ratio f is 1,
• the atomic ratio a and the atomic ratio d satisfy 0.05≤d−a≤0.2, and
• the atomic ratio b and the atomic ratio e satisfy 0.05≤b−e≤0.2,
• wherein a ratio I(200)/I(002) of an intensity I(200) of an X-ray diffraction peak of a (200) plane to an intensity I(002) of an X-ray diffraction peak of a (002) plane in the hard layer is 2 or more and 10 or less,
• a half-value width of the X-ray diffraction peak of the (002) plane is 2° or more and 4° or less, and
• a single underlying layer of unitary composition is provided between and directly contacts the substrate and one of a lowermost first unit laver or a lowermost second unit layer of the hard layer, and a thickness of the single underlying layer is 0.1 μm or more and 2 μm or less.