The present invention relates to a steel for a mold, containing, on a % by mass basis, more than 0.27% to less than 0.36% of C, more than 0.07% to less than 0.40% of Si, more than 7.00% to less than 8.80% of Cr, more than 0.25% to less than 0.80% of Mo, more than 0.50% to less than 0.75% of V, more than 0.0005% to less than 0.05% ofN, and Mn, with the balance being Fe and inevitable impurities, in which an expression of "-0.1Cr + 1.10