PURPOSE: To obtain a highly corrosion resistant metallic material withstanding use even in a severe corrosive environment by forming a prescribed amt. of a plating layer of a Zn-Ti-Mg alloy having a prescribed compounding ratio on the surface of a metallic material.

CONSTITUTION: An alloy plating layer is formed on the surface of a metallic material by vapor phase plating such as vacuum deposition or ion plating by 0.1-60g/m2 coating weight. This plating layer is made of an alloy having a compsn. consisting of 5-60wt.%, in total, of 0.5-50wt.% Ti and 0.5-40wt.% Mg and the balance Zn.