PURPOSE: To suppress the drop of discharge capacity by mixing α-PbO2 in a lead-ACID battery positive electrode plate producing mainly β-PbO2 so as to elongate the life of a battery.

CONSTITUTION: Metallic lead powder where a film is made on the surface is prepared by projecting metallic lead powder into the mixed liquid of polyvinyl acetal dialkyl amino acetate, citric acid, polyvinyl alcohol, and methanol, and drying it after kneading. Lead oxide (mainly lead monoxide) powder, sulfuric acid, and water are kneaded into paste form, and at the stage where the paste changes from acid to alkaline, metallic powder where a film is made is projected and those are kneaded to make paste-form active matter. A transformed anode board is manufactured by charging this paste-form active matter into the collector consisting of lead alloy, and aging and drying it. The film made on the surface of the metallic lead powder is insoluble in neutral or alkaline aqueous solution, and dissolves quickly in acid aqueous solution. When the untransformed anode board is transformed, α-PbO2 is produced together with β--PbO2.