Plating a wire material is provided by a range of plated layer. If the temperature is high and flowability is large then it means it is easily generating thickness deviation, and a range of the plated layer. If the temperature is low and the flowability is small it means the generating thickness deviation only with difficulty are allowed to cool in an appropriate manner. The plating a wire material having an air cooling device provided on an upper portion of a plate-squeezing portion.