To obtain the depth of penetration as same as the normal pulse welding and to reduce the welding defect of bead crack, etc., by repeatedly irradiating on a material with a pulse group composed of plural numbers of laser pulse having a specific interval in a longer interval than its interval.

A normal pulse is, at least, bi-sected, a wave form arranging plural numbers of divided pulse 101 in a row of 0.3 to 1.0 mil-second interval is made as one of pulse group 102, welding is executed by repeatedly irradiating on a material to be welded with this pulse group 102 in the interval as same as the normal pulse. Because this laser welding method is executed to weld while irradiating with plural numbers of high peak output short pulse 102, before the heat of former pulse being escaped, the next pulse is made to be irradiated, so in locally viewing, rapid heating and rapid cooling are relaxed and welding defect is reduced. Figure a is an example of bi-secting pulse, and Figure b is the example of tripartite pulse.