To secure a satisfactory weld quality by irradiating with a laser beam while forming easily and stably a specific gap between both plates in the welding method welding the lap joint of a pair of the plated steel plates by a laser beam.

Surfaces on the one side of first and second plated plates 10, 20 are locally and successively pressured almost vertically by the steel sphere 41 of a local pressing device 40. And, the surfaces on the one side of the first and the second plated plates 10, 20 are successively irradiated almost vertically by the laser beam from a laser beam machine 30 in a position removed by a proscribed distance from this pressure part Thus, the lap joint of the first and the second plated plates 10 and 20 is welded with a satisfactory weld quality.