A welding method, comprising: forming a workpiece by stacking plated sheet members (W1, W2) having a plating layer formed on a surface of a base material; disposing the workpiece in an area to be irradiated with laser light; irradiating a surface of the workpiece with a plurality of beams by dispersing positions such that centers of the beams do not overlap with each other within a prescribed area on the surface, the method being characterised in that: the beams have a Gaussian shape so as to provide a Gaussian power distribution and wherein the dispersing is achieved by a diffractive optical element being configured as a beam shaper comprising a plurality of diffraction gratings of different periods, such that the diffractive optical element is capable of shaping a beam profile by bending or superposing the input laser light toward directions affected by each of the diffraction gratings; while continuing the irradiation, relatively moving the beams and the workpiece and sweeping the beams on the workpiece so as to melt an irradiated part of the workpiece for performing welding; and setting a distance between the beams to be emitted such that weld pools formed in the workpiece by irradiation of each of the beams overlap with each other, wherein the beams are arranged such that any one of the following and applies: an area of the workpiece is irradiated with a plurality of beams with positions thereof being dispersed such that the centres thereof do not overlap with each other within the area, wherein two neighbouring beams partially overlap with each other; and an area of the workpiece is irradiated with a plurality of beams being arranged in a ring-like form, in particular in a circular outer contour, while one of which is arranged in the centre thereof within the area. forming a workpiece by stacking plated sheet members (W1, W2) having a plating layer formed on a surface of a base material; disposing the workpiece in an area to be irradiated with laser light; irradiating a surface of the workpiece with a plurality of beams by dispersing positions such that centers of the beams do not overlap with each other within a prescribed area on the surface, the method being characterised in that: the beams have a Gaussian shape so as to provide a Gaussian power distribution and wherein the dispersing is achieved by a diffractive optical element being configured as a beam shaper comprising a plurality of diffraction gratings of different periods, such that the diffractive optical element is capable of shaping a beam profile by bending or superposing the input laser light toward directions affected by each of the diffraction gratings; while continuing the irradiation, relatively moving the beams and the workpiece and sweeping the beams on the workpiece so as to melt an irradiated part of the workpiece for performing welding; and setting a distance between the beams to be emitted such that weld pools formed in the workpiece by irradiation of each of the beams overlap with each other, wherein the beams are arranged such that any one of the following and applies: an area of the workpiece is irradiated with a plurality of beams with positions thereof being dispersed such that the centres thereof do not overlap with each other within the area, wherein two neighbouring beams partially overlap with each other; and an area of the workpiece is irradiated with a plurality of beams being arranged in a ring-like form, in particular in a circular outer contour, while one of which is arranged in the centre thereof within the area. an area of the workpiece is irradiated with a plurality of beams with positions thereof being dispersed such that the centres thereof do not overlap with each other within the area, wherein two neighbouring beams partially overlap with each other; and an area of the workpiece is irradiated with a plurality of beams being arranged in a ring-like form, in particular in a circular outer contour, while one of which is arranged in the centre thereof within the area.