PURPOSE: To make process line faster and increase quantity of anode oxidation film without extreme increase thereof and burning breakdown on a side end part of an aluminum product which is a band-like matter, at anode oxidation processing in a manufacturing process of a support body for a lithographic plate.

CONSTITUTION: One face to be treated with anode oxidation of an aluminum product is contacted to a feeding roller. In this state, the face is stuck fast also to a support roller 15. The support roller 15 is rotated so as to convey the aluminum product and the aluminum product is cooled to a temperature lower than a temperature of electrolytic solution, and a power source is turned on so as to supply electric current. The supplied current is sent from the feeding roller to the aluminum product. Further, the current flows in the aluminum product to the lowest end part as shown in a drawing and flows into an electrode 12 through an electrolytic solution 14, so that an anode oxidation film is formed on the exposed face of the aluminum product.