Abstract: A sheet material 2 is cut with a round blade 10 and a notching blade 11. It is assumed that, in a straight section P1-P2-P3-P4, a distance between the end point P1 and the end point P2 is not shorter than a blade width W10 of the round blade 10, a distance between the end point P2 and the end point P3 and a distance between the end point P3 and the end point P4 are shorter than the blade width W10 and it is necessary to cut without cutting into a pattern piece indicated by shadow. A section between the end point P2 and the end point P3 can be cut without cutting into the pattern piece although overcut occurs on the end point P2 side, with the round blade 10 by aligning the leading edge thereof at the end point P3. A section between the end point P3 and the end point P4 is cut with the notching blade 11 because cutting with the round blade 10 causes a cut into the pattern piece at least from one of the end points.