PURPOSE: To produce an aluminum material excellent in coating film adhesion and corrosion resistance after coating with good productivity by forming a nonporous anodic oxide film with the thickness, water content and anion content specified on the surface of the Al material.

CONSTITUTION: Al or Al alloy is pretreated to clean its surface and then electrolyzed in an electrolytic bath of boric acid, an adipate, etc., to form a nonporous anodic oxide film having 70-2000μm diameter and contg. 1-5wt.% water and 0.1-7wt.% anion on the surface. At this time, the electrolytic bath is controlled to 15-50°C, the current density to 1-20A/dm2 in DC electrolysis, the electrolyzing time to several sec to 10min and the voltage to be impressed to 5-140V. An Al material appropriately used for the electric appliance, utensil, ornament, etc., is obtained in this way.