PURPOSE: To provide a method for uniformly applying a flux at a prescribed thickness to a wire rod to be plated, etc.

CONSTITUTION: The flux mists generated by imparting ultrasonic waves to a flux soln. 1 are impregnated into a water absorptive fiber assemblage 8 and the wire rod 9 is slid with this water absorptive fiber assemblage 8 impregnated with the flux mists. The flux soln. 1 is uniformly and finely made into the mists at and under ordinary temp. and atm. pressure by the ultrasonic vibrations and, therefore, the entire part of the water absorptive fiber assemblage 8 is uniformly impregnated with the flux. The wire rod 9 is slide with the water absorptive fiber assemblage 8 impregnated with the flux and, therefore, the flux is applied at the prescribed thickness on the wire rod 9. The plated wire which does not cause disconnection, etc., in a later plating stage and has high quality free from pinholes, etc., is, therefore, obtd.