PURPOSE: To enhance the adhesion of a plating layer to a synthetic resin layer by etching the resin layer without causing an excessive reaction and to carry out sure chemical nickel plating on the surface of the resin layer.

CONSTITUTION: When a laminated member obtd. by forming a synthetic resin layer by baking on at least one side of a thin metallic sheet etched to a prescribed pattern is plated, it is baked by heating at 100-250°C for 1-5hr, etched with an etching soln. of an inorg. acid at ordinary temp. to 45°C and successively subjected to sensitivity imparting treatment, activation and chemical nickel plating.