PURPOSE: To perform a cutback quickly with simple operation and to better the finishing by performing a cutback by laser beam.

CONSTITUTION: A laser beam 13 is irradiated from the surface side of a clad steel 1 and laser beam 14 is irradiated on the mating face of the clad steel 1 and base metal 2. The beam intensity of the laser beam 13 and a light source moving speed are adjusted so that the laser beam 13 can pass through the clad steel 1 only. The beam intensity of the laser beam 14 and the light source moving speed are adjusted so as to cut off the depth in the separating width part only. By using these laser beams 13. 14 the face after the cutback becomes flat and the finishing becomes better as well.