LASER PIERCING METHOD

PROBLEM TO BE SOLVED: To provide a laser piercing method by which a hole having the diameter of a degree to which drilling is smoothly shiftable to cutting is formed in a short time by irradiating a material to be cut with a laser beam.SOLUTION: In the laser piercing method by which a through-hole 8 in the thickness direction is formed on the material to be cut by irradiating the material B to be cut with the laser beam 7 and also jetting assist gas composed of gaseous oxygen from a laser nozzle A to the material B to be cut, in the state where the focus S of the laser beam 7 is set in a position in the inside direction of a plate thickness of the material B to be cut and where the position is held, the material B to be cut is irradiated from the laser nozzle A with a pulse-like laser beam, the peak output of which is ≥50% of the rated output of a laser oscillator 11 and the duty ratio of which is set to ≥50%, also the assist gas which is set to lower pressure than the pressure of the assistant gas which is suitable to cut the material B to be cut is jetted and shield gas containing the gaseous oxygen is jetted to the outside of the assist gas.