PURPOSE: To improve the voltage efficiency of a battery by coating the surface of a plastic electrode with a conductive coat and diffusing conductive powder immediately before curing to touch and curing the powder.

CONSTITUTION: When a plastic electrode is formed by using olefin resin such as bromine-proof polyethylene and polyproylene as the raw material, the material obtained by mixing and diffusing the carbon black of normally 5∼50wt% is used. A conductive coat that is diffused in a vehicle with the adhesion or compatibility for the olefin resin is required and carbon black, silver powder or the like is used as the material that shows the conductive function. After the surface of the plastic electrode is coated with the conductive coat, conductive powder is diffused before the surface of the coat is cured in such a degree to touch. As the conductive powder, carbon black, platinum black or mixture of these materials whose particle diameter is approximately 15∼400nm or desirable 30∼ 50nm is used and the diffusion thickness is approximately 5∼100μm or desirably 10∼50μm.