A laser welding method comprising: disposing a first boundary portion of a first member, being a metal member having an oxide film, and a second boundary portion of a second member, being a metal member having an oxide film, such that a first boundary surface of the first boundary portion and a second boundary surface of the second boundary portion face each other, the first boundary portion and the second boundary portion extending along a boundary between the first member and the second member; and moving an irradiation position of a multiple laser beam in an advancing direction along the boundary, and irradiating the multiple laser beam to the first boundary portion of the first member and the second boundary portion of the second member to melt the first boundary portion and the second boundary portion so as to weld the first member and the second member together, wherein: the multiple laser beam includes a first beam that is irradiated to the first boundary portion of the first member and advanced in the advancing direction along the boundary while melting the first boundary portion, a second beam that is irradiated to the second boundary portion of the second member and advanced in the advancing direction along the boundary synchronously with the first beam while melting the second boundary portion, and a main beam that has an energy higher than an energy of each of the first beam and the second beam and is advanced on the boundary in the advancing direction along the boundary subsequently to and synchronously with the first beam and the second beam and irradiated to an integrated molten pool formed by integration of a first molten pool in which the first boundary portion is melted by the first beam, and a second molten pool in which the second boundary portion is melted by the second beam; characterised in that: the first beam and the second beam do not swing, and the main beam swings with respect to the boundary. disposing a first boundary portion of a first member, being a metal member having an oxide film, and a second boundary portion of a second member, being a metal member having an oxide film, such that a first boundary surface of the first boundary portion and a second boundary surface of the second boundary portion face each other, the first boundary portion and the second boundary portion extending along a boundary between the first member and the second member; and moving an irradiation position of a multiple laser beam in an advancing direction along the boundary, and irradiating the multiple laser beam to the first boundary portion of the first member and the second boundary portion of the second member to melt the first boundary portion and the second boundary portion so as to weld the first member and the second member together, wherein: the multiple laser beam includes a first beam that is irradiated to the first boundary portion of the first member and advanced in the advancing direction along the boundary while melting the first boundary portion, a second beam that is irradiated to the second boundary portion of the second member and advanced in the advancing direction along the boundary synchronously with the first beam while melting the second boundary portion, and a main beam that has an energy higher than an energy of each of the first beam and the second beam and is advanced on the boundary in the advancing direction along the boundary subsequently to and synchronously with the first beam and the second beam and irradiated to an integrated molten pool formed by integration of a first molten pool in which the first boundary portion is melted by the first beam, and a second molten pool in which the second boundary portion is melted by the second beam; characterised in that: the first beam and the second beam do not swing, and the main beam swings with respect to the boundary.