Piercing processing method and laser processing machine

A laser processing machine for carrying out a piercing processing on a metallic material by laser beams with wavelengths in 1 μm waveband, the laser processing machine comprising:

• a fiber laser oscillator for oscillating the laser beams with the wavelengths in 1 μm waveband;
• a process fiber connected to a laser processing head for carrying out the piercing processing on the metallic material;
• a beam quality tuner configured to transmit the laser beams oscillated from said fiber laser oscillator to said process fiber;
• and
• a controller configured to control said beam quality tuner such that a relationship between a condensed beam diameter d and a Rayleigh length Zr of the laser beams to be irradiated onto the metallic material from said laser processing head is maintained to be in a range of 8≤Zr/d≤12, wherein
• said beam quality tuner is set such that a profile of the laser beams satisfy 8≤Zr/d≤12 during piercing.