PURPOSE: To make base preparation simple and improve the adhesion strength between a non-etched part of an aluminum-based material and a resin by using a resin having a function as a primer for a fluororesin coating as an ink for a resist printing.

CONSTITUTION: Prior to coating a metal material such as an aluminum-based material for a rice cooking jar, a rice cake maker, etc., with a fluororesin, an aluminum plate 1 is degreased with an aqueous sodium hydroxide solution and then the surface of the plate is coated lattice pattern-wise with an etching resist 2 by screen printing. A tetrafluoroethylenic resin, etc., having a function as a primer for a fluororesin coating is used as the ink for the resist printing. And then, the plate is etched and coated with a fluororesin. By this method, base preparation can be carried out simply without resist removal process and adhesion strength of non-etched parts of the aluminum plate to the resin is improved.