To display the difference of workings by the difference of cutting shapes by providing a cutting pattern storage means, a cutting shape generation means, a cutting shape storage means storing cutting shape data and a cutting shape display means displaying the stored cutting shape data.

A cutting shape generating part 13 takes out the edge passing area data D9 as edge passing area data D16 if edge passing area data D9 is registered in an edge passing area storage part 9. Continuously, the cutting pattern data D13 secured in a cutting pattern storage part 12 is taken out as cutting pattern data D14. Further, cutting pattern data D14 is erased from the edge passing area data D16 and cutting shape data 15 is generated. Cutting shape data D15 is registered in a cutting shape storing part 14. A cutting shape displaying part 10 takes out cutting shape data 15 as cutting shape data D10 every time cutting shape data 15 is registered, generates display data D11 and transmits data D11 to a CRT 7.