A spring characterized by: having a total composition comprising, in terms of wt%, 0.27-0.48% of C, 0.01-2.2% of Si, 0.30-1.0% of Mn, not more than 0.035% of P, and not more than 0.035% of S, the balance being Fe and inevitable impurities; the thicknesses of a nitrogen compound layer and carbon compound layer on the surface being not more than 2 [mu]m; the hardness at the center part of the cross section being 500-700 HV; a compressive residual stress layer with a thickness of 0.30 mm to D/4 [wherein D stands for the circle equivalent diameter (mm) of the cross section] being formed in the surface layer; and the maximum compression residual stress thereof being 1400-2000 MPa.