A method for manufacturing a lead frame including the steps of electrocleaning the surface of a thin plate material, electropolishing the electrocleaned thin plate material, removing inclusions on the surface of the electropolished thin plate material, rinsing the inclusion-removed thin plate material with an acidic solution, and forming multi-plated layers on the rinsed material. The lead frame manufactured by the method has 5 or less inclusions each having approximately 1 &mgr;m, on the surface area of 1600 &mgr;m2, which impede a wire bonding property or solder wettability of the lead frame.