A laser processing machine having a laser beam irradiation unit is provided. The laser beam irradiation unit includes: a laser beam oscillation section; a beam splitter adapted to split the laser beam emitted from the laser beam oscillation section into a first laser beam and a second laser beam; a condenser lens adapted to condense the first and second laser beams; a prism adapted to lead the first and second laser beams split by the beam splitter to the condenser lens; a first angle-changing mirror disposed on a first optical path adapted to lead the first laser beam split by the beam splitter; a second angle-changing mirror disposed on a second optical path adapted to lead the second laser beam split by the beam splitter to the prism; and a half-wave plate disposed in the first or second optical path to allow one of respective directions of the first and second polarization planes to be aligned with the other.