PURPOSE: To engrave uniform breaks and to obtain a uniform high-quality product by moving a cutter attached to a rocking shaft so as to describe a flat elliptic locus and carrying out cutting at the lower half part of the locus.

CONSTITUTION: A rocking shaft 23 is vertically moved in a shaft holder 24 with eccentric rotation of an eccentric shaft 22 and a holder supporting shaft 28 is revolved around a shaft in an integrated way with the shaft holder. A cutter 27 attached to the rocking shaft is moved while describing a flat elliptic locus and cutting is carried out at the lower half part coincident with progress direction of a raw material sheet of the locus.