PURPOSE: To sufficiently seal the pinhole part in a goldplated material and to improve corrosion resistance and wear resistance by applying ultrasonic waves to the surface of a gold-plated or gold-alloy-plated material and carrying out sealing treatment.

CONSTITUTION: A material plated with gold or gold alloy is immersed into a treatment solution of an organic amine, etc., by which sealing treatment is applied to the surface of the above material. At this time, the above treatment is carried out by applying ultrasonic waves, by which the reactivity between the sealant and the substrate can be improved, and the pinhole part can sufficiently be sealed. By the above sealing treatment, the gold-plated or gold-alloy- plated material excellent in corrosion resistance and wear resistance can be obtained.