PURPOSE: To improve the adhesion of plating layers to steel strip surfaces and prevent the occurrence of non-plating by accomplishing the removal of the thick oxides on the steel strip surfaces by an action of the plating bath itself as a technical subject.

CONSTITUTION: The plating bath 2 which comes into contact with the surfaces of the steel strip S right after introduction into the plating bath 2 is compulsorily fluidized at ≥1m/sec flow velocity in a direction opposite to the progressing direction of the steel strip S, by which the reducing effect of the aluminum in the plating bath 2 is activated and the reaction of the plating bath 2 with the steel strip S is activated.