Abstract: The present invention provides, at low cost, a valve spring steel having a tensile strength as high as 210 to 240 kgf/mm.sup.2 after oil tempering. The high strength spring steel comprises, based on weight, 0.65 to 0.85% of C, 1.90 to 2.40% of Si, 0.50 to 1.00% of Mn, 0.70 to 1.30% of Cr, 0.10 to 0.30% of Mo, 0.20 to 0.50% of V, 0.01 to 0.04% of Nb and the balance Fe and unavoidable impurities and is subjected to heating at temperature of 1,050 to 1,250.degree. C. and then to rolling so that carbides in the steel have a size of up to 0.15 .mu.m in terms of equivalent circle. A valve spring having a tensile strength as high as 210 to 240 kgf/mm.sup.2 after oil tempering and stabilized quality can be produced while the material cost is greatly reduced by decreasing costly alloying components as much as possible.