A laser groove machining method for forming bottomed grooves in a surface
of a workpiece using a laser, wherein an emitting position of a laser
beam which is to be emitted onto the workpiece is shifted relatively
along groove forming positions at a high speed of 150 mm/min. or faster.
Thus, melted portions which are melted by the laser beam can easily be
separated, cooled and removed by shifting the laser beam emitting
position at high speed. In addition, water may be jetted to the workpiece
so as to form a pillar of water so that the laser beam is emitted through
the interior of the pillar of water so formed.