PURPOSE: To perform elimination or reduction of labor in the step of constructing a welded structure, by depositing a weld metal onto a parent metal by gas- shielded welding, applying thermosetting resin-contg. paint onto the surface of the bead of the weld metal, etc., and curing said paint with residual weld heat.

CONSTITUTION: During a cooling step after a weld metal 4 is deposited onto a parent metal 2 by gas-shielded welding, an applicator nozzle 7 is let run following the advancing direction D of an arc, so that paint 8 containing thermosetting resin such as melamine one is sprayed through the nozzle 7 and applied onto the surface 4a of the bead and its vicinity. Thereafter the paint 8 is cured using residual weld heat remaining in said weld metal 4 and its vicinity, to form a coating film 9 at the surface 4a of the bead, etc. Since this method enables to form the coating film 9 immediately after the welding, complicated brushing works such as the removal of hygroscopic components in advance of the coating can be eliminated.