PURPOSE: To improve the efficiency in working, by synthesizing laser beams, dividing the synthesized laser beam and performing multi-point working.

CONSTITUTION: A beam splitter 5 is provided near the intersected point of the 1st laser beam 3 and the 2nd laser beam 4 oscillated respectively from a continuously oscillating CO2 laser device 1 and a pulse oscillating CO2 laser device 2. The laser beam 6 multiplex and demultiplex by a beam splitter 5 arrives directly at the working point 9 of the work 8 and is condensed by a condenser lens 7, whereby the working is accomplished. Another laser beam 6' demultiplexed therefrom arrives at another working point 9' of the work 8 from 3 pieces of reflecting mirrors 10 and is condensed by another condenser lens 7', whereby the working is accomplished. The bite of working in the work is thus improved, the ejection of the working debris is accelerated and the satisfactory working is effected with good efficiency.