Abstract: A continuous electrolytic treatment apparatus for anodic oxidation and electrolytic coloring operations on an object such as a strip, wire or foil of aluminum and its alloys, wherein there are provided electric field buffer means which comprises a plurality of self-standing plates of plastic resin or the like having an electrically insulating property. The electric field buffer means are located at least in one zone in the electrolytic cell so that it can serves to effectively buffer concentration of excessive electric current to the interface between the object and the electrolytic solution at the above mentioned zone, thereby preventing burning in the surface of the object or in the oxide film formed thereon during the anodic oxidation treatment and unevenness in coloring of the object during the electrolytic coloring operation due to such current concentration, particularly when treating with a high current density.