PURPOSE: To elevate rust prevention property and to decrease variations of plating thickness by performing current application galvanization to the whole face of a laminate electromagnet iron core, and treating it in chromic acid solution.

CONSTITUTION: The plating process of a pole contact face 3 between a movable iron core 1 and a fixed iron core 2 is done in the steps of degreasing → current application galvanization (not more than 5μ) → washing → hot washing →chemical polishing → washing → chromate treatment → washing → drying →chromic acid treatment → drying. And by performing galvarization on the whole face including parts other than the pole contact face 3 and treatment by chromic acid solution, the process can be shortened by omitting a plating process.