This steel has a chemical composition which contains, in mass%, 0.16-0.30% of C, 0.01-2.0% of Si, 0.35-1.45% of Mn, 0.05-3.0% of Cr, 0.001-0.2% of Al, 0.04-5.0% of Ni, 0.015%-1.0% of Sn, 0.004-0.05% of S, 0.003-0.03% of N, 0.005% or less of O, 0.025% or less of P, 0-1.0% of Mo, 0-1.0% of Cu, 0-0.005% of B, 0-0.3% of Nb, 0-0.3% of Ti, 0-1.0% of V, 0-0.01% of Ca, 0-0.01% of Mg, 0-0.05% of Zr, 0-0.1% of Te and 0-0.005% of a rare earth element, with the balance made up of Fe and impurities. If [Si%], [Ni%], [Al%] and [Sn%] are the contents of Si, Ni, Al and Sn in terms of mass%, the relation 42 ≥ 21 × [Si%] + 5 × [Ni%] + 40 × [Sn%] + 32 × [Al%] ≥ 8.5 is satisfied.