A development of a laser cutting method and a laser cutter in which the adverse effects such as self burning to the cutting surface can be prevented, when the material is cut at a high speed, has been desired. In order to achieve the object, the present invention provides a laser cutting method and a laser cutter in which a cutting laser beam 22 is applied to a material 25 to be cut at a cutting point 26, while ejecting gases 23 and 24 to the cutting point 26 or its surrounding area from a plurality of nozzle openings 30 and 31 arranged in a ring or in a line, wherein the oxygen concentrations of the gases 23 and 24 ejecting from at least one of the nozzle opening 30 and 31 are changed to adjust the oxygen concentration distribution in an area within several millimeters of the cutting point 26; thereby the cutting quality can be improved.