PURPOSE: To prevent molten metal from passing around behind the single side to be plated, by introducing pretreated continuous hoop into nonoxidizing atmosphere, by spraying molten metal through nozzles or slits arranged laterally so that the more apart is the nozzle from the central part, the less is the molten metal sprayed through the nozzle.

CONSTITUTION: Steel hoop 2, heated in a furnace 1 and its surface is cleaned, enters through a sealing part 3, a snout 4 to a plating chamber 5, conveyed upward through a roll 6, then led through a sealing part 7, cooling tower 8, and sealing part 9 to the outside air. In that case, under surface of the hoop 2 is plated with molten metal flow 12 sprayed through nozzles 11 arranged laterally. The spraying quantity of molten metal flow 12 is not uniform over whole lateral direction of the slits or nozzles 11, that is the spraying quantity at the end is smaller than that at the central part, forming arch shape shown by figure.