Provided is a method for manufacturing a lead frame and a semiconductor package having a semiconductor chip for connecting to an outer board and having a base metal layer formed of iron and nickel as main elements. The method includes preparing the base metal layer of a lead frame, forming one or more plating layers on the base metal layer, mounting the semiconductor chip on the lead frame, molding the semiconductor chip and at least a portion of the lead frame, bending the lead frame to form the lead frame in a predetermined shape, and heat-treating the lead frame for forming a diffusion layer in order to protect the lead frame from corrosion.