This steel has a steel sheet substrate and a protective film formed on at least a part of a surface of the steel sheet substrate, the chemical composition of the steel sheet substrate is, by mass %, C: 0.25% to 0.65%, Si: 0.05% to 2.00%, Mn: 0.30% to 3.00%, P: 0.050% or less, S: 0.0100% or less, N: 0.010% or less, O: 0.010% or less, Cr: 0.05% to 1.00%, and Cu: 0.10% to 1.00%, in an X-ray analysis in which measurement is carried out using a CuKα radiation, in a case where a peak intensity at a diffraction angle (2θ) position of 36.6±0.5° is regarded as 100%, the protective film has a peak having a peak intensity of more than 250% at a diffraction angle (2θ) position of 35.5±0.5° and a tensile strength is more than 1,500 MPa.