PURPOSE: To improve the adhesion of ink by a method wherein the metallic material is subjected to a corona discharge treatment, then printing is conducted by using an ultraviolet-curing ink, and the ink is cured by radiating ultraviolet rays thereto.

CONSTITUTION: Tinplate, steel, aluminum, copper or the like is used as the metallic material. In carrying out the corona discharge treatment, a corona discharge device having an output of about 1W10kw is used and the electrode system is modified, as required, to adapt it to the conductive material. The ultraviolet-curing ink is selected from those inks which are dryable by photo-polymerization utilizing radical polymerization, and may comprised of various reactive prepolymers, reactive monomers, polymerization initiators, pigments, additives, stabilizers, etc.