To obtain a laser beam machining apparatus which can easily provide improved positional accuracy of the machined hole(s) and reduction in the generation of strain, when a plurality of holes are simultaneously machined using an HOE (holographic optical element) or single slot machining is performed without using an HOE.

The laser beam machining apparatus is equipped with: the HOE 10 of dispersing a laser beam 1 into a plurality of laser beams; two galvanoscanners where the dispersed laser beams are two-dimensionally allowed to scan to the directions almost orthogonal each other in such a manner that the corresponding mirror faces 2a, 2b are rotatively driven; and an f lens 4 of condensing/emitting the two-dimensionally scanned laser beams toward a workpiece, wherein on the mirror face 2a rotatively driven by the galvanoscanner receiving the laser beam at first, laser beam is incident in such a state that the longitudinal direction side of the dispersed pattern 14a of the laser beam dispersed at the HOE10 faces the axial line direction side of the driving axis of the galvanoscanner. Thus, the pattern rotation angle at the edge part of a scan area 7 is made small, and the positional accuracy improves.