PURPOSE: To prevent the generation of omission and a projection part on the hole inner periphery by controlling an output condition and a machining condition of a laser beam to proper values at the same time according to the cutting position on a drilling and cutting path.

CONSTITUTION: A workpiece and the laser beam are moved relatively so that drilling work of specified dimensions can be performed after the laser beam passes a straight line passing the hole center of the workpiece and a small circular arc (point (b) from point (a)) to the extent of R1 to inscribe the hole inner periphery. The irradiation of the laser beam passes a point (c) and then, is further continued up to a point (d) identical with the point (b) and stopped. At this time, the laser beam output, pulse duty, cutting speed and machining gas pressure of the machining condition are controlled to the proper values at the same time according to the cutting position on the drilling and cutting path (the hole center → the point (a) → the point (b) → the point (c) → the point (d)).