PURPOSE: To always nearly parallelize a laser beam without originating in the divergence angle of the laser beam emitted from a laser generator and to have this parallelized laser beam taken in a laser beam machining head without reference to the length of a light path.

CONSTITUTION: The laser beam machine 1 is provided with the laser machining head 11 which is freely movable at least to one axial direction, and is also provided with a laser beam parallelization processing device 17 near the exit of the laser generator 15 so as to always nearly parallelize the laser beam LB without reference to the variation of the length of the light path in the laser beam LB from the emission out of the laser generator 15 to the laser beam machining head 11. Also, the laser beam parallelization processing device 17 is constituted of a polarizing mirror 21, convex mirror 23 and concave mirror 25.