PURPOSE: To extremely decrease the pressing flaws to be generated on a painted surface by polishing the weld zone of steel strips and the periphery thereof to peel and remove the splashes generated at the time of welding, sticking an adhesive tape thereto, allowing the steel strips stuck with the adhesive tape to travel and subjecting the steel strips to continuous painting.

CONSTITUTION: The front end of the steel strip 2 un-coiled from a payoff reel 1 and the rear end of the preceding steel strip are connected by narrow lap welding. The connected steel strips are then made to travel at a low speed and are sent to a polishing section 20. Brushing rolls 21a, 21b provided with many wires in the form of brushes around the rolls are disposed above the below the steel strip 2. The rotating brushing rolls 21a, 21b are brought into contact with the steel strip 2 to polish the weld zone of the steel strip 2 and the range where the splashes before the behind the weld zone are deposited, by which the splashes are peeled. The steel strip the weld zone of which is polished in such a manner is stuck with the adhesive tape in a taping device 30. The product yield is greatly improved in this way.