Abstract: A device according to the invention comprises trolleys arranged above a plating bath and movable in transverse directions of a steel strip, guide rollers secured to lower ends of vertical levers depending from the trolleys and in contact with edges of the strip by urging means such as counter weights acting upon the vertical levers, and shielding plates secured to the lower ends of the vertical levers below the guide rollers so as to shield undersides of the strip in the proximity of the edges from anodes immersed in the plating bath in opposition to the strip.The device according to the invention can maintain the positional relation between the edges of the strip and shielding plates notwithstanding staggering movements of the strip to prevent the edges of the strip from being excessively plated.