PROBLEM TO BE SOLVED: To provide a femtosecond laser processing machine making it possible to shorten a required time by expanding a processed area of irradiation per work time, which is related to a versatile labor-saving processing method, in processing that employs a femtosecond laser.SOLUTION: A light-source beam 21 oscillated from a femtosecond laser oscillator 19 is separated into a primary optic-axis beam 1 and plural branch beams 2 and 3 whose optical lengths are different from each other. An integrated beam 4 to and on which the primary optic-axis beam 1 and branch beams 2 and 3 are returned and concentrated is introduced into a condenser lens 7 in order to cause a time lag at the time of irradiation due to the difference in the optical length between the plural branch beams 2 and 3. The lens center position of the condenser lens 7 is deviated from the optical-axis center of the integrated beam 4. In addition, the condenser lens 7 is rotated about the optical-axis center of the integrated beam 4. Further, a work 41 that is an object of processing is moved, and the work 41 is continuously irradiated, whereby an irradiation trajectory is horizontally moved along the plane to be processed of the work 41, and thus shaped like a horizontal spiral. Besides, an irradiation focal area is expanded in an arc-like form.
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