PURPOSE: To increase bending angle and to reduce working cost by irradiating the laser beam from a bisector of the supplementary angle for the bend angle, in the stage of bending the work stock with irradiating the laser beam.

CONSTITUTION: A fixing jig 5, rotating motor 6 for the jig, displacement sensor 9 and its driving device 10 are disposed on the work 1 side and on the laser beam irradiating side, a driving device 8 for the laser beam converging and irradiating part and the converging and irradiating part 7 are set up. The bending part of the work stock 1 is irradiated with the laser beam 2 through the laser converging and irradiating part 7, and the driving part 8 performes beam scaning along with the bending direction of the work stock 1. In this case, the working control is performed to make the optical axis of the laser to exist on the bisector of the supplementary angle of the angle θ detected by the sensor 9. By this method, the irradiating heat balance is equarized, a needless thermal deformation is prevented and the bending angle is increased 90°.