To provide a method for inexpensively and reliably surface-treating ferro-alloy electronic parts, by using a metal which does not include lead and tin, and has adequate wettability to solder.

This surface treatment method comprises the steps of: pickling a ferro-alloy base material 1 to strongly activate it and form a passivated film on the surface; forming a thin nickel film 5 with a strike plating method on the surface of the ferro-alloy base material 1; washing it with water; forming a thicker nickel film 2 than the strike-plated nickel film 5 on the nickel film 5; and forming a strike-plated palladium film 3 on the nickel plated film 2 and the lap-plated gold film 4 thereon by electrolytic plating treatment, so that the strike-plated palladium film 3 can acquire a thickness in a range of 0.007 to 0.1 μm, the lap-plated gold film 4 can acquire a thickness in a range of 0.003 to 0.02 μm, and both thicknesses can satisfy a relationship of: thickness of lap-plated gold film 4 is less than thickness of strike-plated palladium film 3.