PURPOSE: To improve productivity and eliminate the decrease or the iregularity of electrostatic capacity, by a method wherein, after an aluminum electrode plate is etched, or after further an anode oxide film layer is formed, the electrode plate is cut by using a high density energy heat source.

CONSTITUTION: A foil formed by caldding Al alloy foils manufactured by a quench solidification method on both sides of an aluminum foil is subjected to etching treatment and formation treatment to form a capacitor electrode plate 1, the surface and the rear of which are composed of etching.formation layer 2 and the intermediate layer of which is composed of a pure metal (Al) layer 3. The capacitor electrode plate 1 is cut by casting a laser beam 6 from the electrode element surface. Thereby cutting is enabled without applying mechanical load to the electrode material of a belt type or a large plate subjected to etching and formation treatment, and a cut part where etching structure is not broken down can be obtained.