To provide a laser welding method capable of well welding two resin molded objects in a state providing a gap between the surfaces to be welded of both resin molded objects.
In a first molded object and a second molded object of which the transmissivity of light with a wavelength of 500-1,200 nm is lower than that of the first molded object, either one of carbon dioxide, nitrogen and water is added to at least the surface layer of the second molded object as a foaming agent and the foaming agent is foamed to be expanded in its volume by the heat occurring from the surface layer at the time of laser welding to fill the gap present between the surfaces to be welded of both resin molded objects with the surface layers expanded in its volume of the second resin molded object to integrally weld both resin molded objects.
KURAMITSU MASATO
MUROBOSHI TATSUKI
