Patent ID: 8828306

Claim:
A working object cutting method for cutting a planar working object along a plurality of cutting-scheduled lines, the method comprising the steps of: irradiating the working object with a laser beam while locating a converging point within the working object, so as to form a reformed region in the working object along a reformed-region forming line set at a predetermined distance inside from an outer edge of the working object along the outer edge; forming a cutting start region along the cutting-scheduled lines; and cutting the working object along the cutting-scheduled lines from the cutting start region acting as a start point, wherein the working object is shaped like a disc, the reformed-region forming line has an annular form extending along the outer edge of the working object and the reformed region is generated by relatively and annularly moving the laser beam with respect to the working object while irradiating the working object to generate the reformed region within the object, and the cutting-scheduled lines are set like grids located inside of the reformed-region forming line.