A steel sheet comprising an inner layer and a hard layer on one or both surfaces of the inner layer, the steel sheet characterized in that a thickness of the hard layer is 20 μm or more and 40% or less of a thickness of the steel sheet, an average micro-Vickers hardness of the hard layer is 240 HV or more and less than 400 HV, an amount of C of the hard layer is 0.4 mass% or less, an amount of N of the hard layer is 0.02 mass% or less, a standard deviation of a variation of hardness measured by a nanoindenter at a depth of 10 μm from a surface of the hard layer, determined in accordance with the description, is 2.0 or less, an average micro-Vickers hardness of the inner layer, determined in accordance with the description, is 80 HV or more and less than 400 HV, a volume rate of carbides contained in the inner layer is less than 2.00%, and the average micro-Vickers hardness of the hard layer is 1.05 times or more the average micro-Vickers hardness of the inner layer, wherein the hard layer contains, by mass%, C: 0.03 to 0.35%, Si: 0.01 to 3.00%, Mn: 0.70 to 10.00%, P: 0.0200% or less, S: 0.0200% or less, Al: 0.500% or less, N: 0.0200% or less, O: 0.0200% or less, Ti: 0 to 0.500%, B: 0 to 0.0100%, Cr: 0 to 2.000%, Mo: 0 to 1.000%, Nb: 0 to 0.500%, V: 0 to 0.500%, Cu: 0 to 0.500%, W: 0 to 0.100%, Ta: 0 to 0.100%, Ni: 0 to 0.500%, Sn: 0 to 0.050%, Sb: 0 to 0.050%, As: 0 to 0.050%, Mg: 0 to 0.0500%, Ca: 0 to 0.050%, Y: 0 to 0.050%, Zr: 0 to 0.050%, La: 0 to 0.050%, Ce: 0 to 0.050%, and a balance of Fe and impurities and the inner layer contains, by mass%, C: 0.001 to 0.300%, Si: 0.01 to 3.00%, Mn: 0.10 to 3.00%, P: 0.0200% or less, S: 0.0200% or less, Al: 0.500% or less, N: 0.0200% or less, O: 0.0200% or less, Ti: 0 to 0.500%, B: 0 to 0.0100%, Cr: 0 to 2.000%, Mo: 0 to 1.000%, Nb: 0 to 0.500%, V: 0 to 0.500%, Cu: 0 to 0.500%, W: 0 to 0.100%, Ta: 0 to 0.100%, Ni: 0 to 0.500%, Sn: 0 to 0.050%, Sb: 0 to 0.050%, As: 0 to 0.050%, Mg: 0 to 0.0500%, Ca: 0 to 0.050%, Y: 0 to 0.050%, Zr: 0 to 0.050%, La: 0 to 0.050%, Ce: 0 to 0.050%, and a balance of Fe and impurities. an inner layer and a hard layer on one or both surfaces of the inner layer, a thickness of the hard layer is 20 μm or more and 40% or less of a thickness of the steel sheet, an average micro-Vickers hardness of the hard layer is 240 HV or more and less than 400 HV, an amount of C of the hard layer is 0.4 mass% or less, an amount of N of the hard layer is 0.02 mass% or less, a standard deviation of a variation of hardness measured by a nanoindenter at a depth of 10 μm from a surface of the hard layer, determined in accordance with the description, is 2.0 or less, an average micro-Vickers hardness of the inner layer, determined in accordance with the description, is 80 HV or more and less than 400 HV, a volume rate of carbides contained in the inner layer is less than 2.00%, and the average micro-Vickers hardness of the hard layer is 1.05 times or more the average micro-Vickers hardness of the inner layer, wherein the hard layer contains, by mass%, C: 0.03 to 0.35%, Si: 0.01 to 3.00%, Mn: 0.70 to 10.00%, P: 0.0200% or less, S: 0.0200% or less, Al: 0.500% or less, N: 0.0200% or less, O: 0.0200% or less, Ti: 0 to 0.500%, B: 0 to 0.0100%, Cr: 0 to 2.000%, Mo: 0 to 1.000%, Nb: 0 to 0.500%, V: 0 to 0.500%, Cu: 0 to 0.500%, W: 0 to 0.100%, Ta: 0 to 0.100%, Ni: 0 to 0.500%, Sn: 0 to 0.050%, Sb: 0 to 0.050%, As: 0 to 0.050%, Mg: 0 to 0.0500%, Ca: 0 to 0.050%, Y: 0 to 0.050%, Zr: 0 to 0.050%, La: 0 to 0.050%, Ce: 0 to 0.050%, and a balance of Fe and impurities and C: 0.03 to 0.35%, Si: 0.01 to 3.00%, Mn: 0.70 to 10.00%, P: 0.0200% or less, S: 0.0200% or less, Al: 0.500% or less, N: 0.0200% or less, O: 0.0200% or less, Ti: 0 to 0.500%, B: 0 to 0.0100%, Cr: 0 to 2.000%, Mo: 0 to 1.000%, Nb: 0 to 0.500%, V: 0 to 0.500%, Cu: 0 to 0.500%, W: 0 to 0.100%, Ta: 0 to 0.100%, Ni: 0 to 0.500%, Sn: 0 to 0.050%, Sb: 0 to 0.050%, As: 0 to 0.050%, Mg: 0 to 0.0500%, Ca: 0 to 0.050%, Y: 0 to 0.050%, Zr: 0 to 0.050%, La: 0 to 0.050%, Ce: 0 to 0.050%, and a balance of Fe and impurities and the inner layer contains, by mass%, C: 0.001 to 0.300%, Si: 0.01 to 3.00%, Mn: 0.10 to 3.00%, P: 0.0200% or less, S: 0.0200% or less, Al: 0.500% or less, N: 0.0200% or less, O: 0.0200% or less, Ti: 0 to 0.500%, B: 0 to 0.0100%, Cr: 0 to 2.000%, Mo: 0 to 1.000%, Nb: 0 to 0.500%, V: 0 to 0.500%, Cu: 0 to 0.500%, W: 0 to 0.100%, Ta: 0 to 0.100%, Ni: 0 to 0.500%, Sn: 0 to 0.050%, Sb: 0 to 0.050%, As: 0 to 0.050%, Mg: 0 to 0.0500%, Ca: 0 to 0.050%, Y: 0 to 0.050%, Zr: 0 to 0.050%, La: 0 to 0.050%, Ce: 0 to 0.050%, and a balance of Fe and impurities. C: 0.001 to 0.300%, Si: 0.01 to 3.00%, Mn: 0.10 to 3.00%, P: 0.0200% or less, S: 0.0200% or less, Al: 0.500% or less, N: 0.0200% or less, O: 0.0200% or less, Ti: 0 to 0.500%, B: 0 to 0.0100%, Cr: 0 to 2.000%, Mo: 0 to 1.000%, Nb: 0 to 0.500%, V: 0 to 0.500%, Cu: 0 to 0.500%, W: 0 to 0.100%, Ta: 0 to 0.100%, Ni: 0 to 0.500%, Sn: 0 to 0.050%, Sb: 0 to 0.050%, As: 0 to 0.050%, Mg: 0 to 0.0500%, Ca: 0 to 0.050%, Y: 0 to 0.050%, Zr: 0 to 0.050%, La: 0 to 0.050%, Ce: 0 to 0.050%, and a balance of Fe and impurities.