Stainless steel sheet and method for producing same

A stainless steel sheet suitable for precision machining comprises, in mass%, not more than 0.030% of C, not more than 0.80% of Si, not more than 1.20% of Mn, not more than 0.045% of P, not more than 0.01% of S, not more than 0.60% of Cu, not more than 0.60% of Mo, not more than 0.02% of Al, not more than 19.0 and not less than 18.0% of Cr, not more than 9.0% and not less than 8.0% of Ni, not more than 0.1% and not less than 0.03% of Nb and not more than 0.1% and not less than 0.02% of N, with the balance being iron and impurities, wherein the Md30 value as defined by a formula (1) is 25 to 55, and the average crystal grain diameter is 5 mum or less. The formula (1) is Md30 = 497-462(C+N)-9.2(Si)-8.1(Mn)-13.7(Cr)-20(Ni+Cu)-18.5(Mo), wherein In formula (1), C, N, Si, Mn, Cr, Ni, Cu and Mo respectively represent the contents (unit: mass%) of the corresponding elements in the steel.