Provided is a laser lap welding method including the steps of: preparing two steel sheets, at least one of which is a galvanized steel sheet, in such a manner that the steel sheets are directly lapped one over the other with a galvanized layer of the galvanized steel sheet located as an interface of the steel sheets; and irradiating an outer surface of any one steel sheet in the lap region of the two steel sheets with a laser beam under predetermined power and speed conditions, so that an elongated hole is formed in a molten pool extending backward from a laser irradiation position at least in the steel sheet on the outer surface side. Welding of the two steel sheets is performed while venting metal vapor produced by the laser irradiation through the elongated hole backwards in a laser travelling direction and towards a laser irradiation source.