PURPOSE: To decrease an amount of artwork data corresponding to an area pattern and to shorten the generation time even if an area pattern of complicate shape is included in the pattern of the designed printed board.

CONSTITUTION: An artwork data generation part 2 which inputs designed printed board pattern information is provided. A lead aperture with the maximum line width is selected 3 first, an area which can be drawn is cut 4 from respective area patterns of the pattern information, and artwork data as to the cut area is generated 5. Further, an area which can be drawn is cut with an aperture having the next large line width from the remaining area of the area cut from each area pattern of the pattern information to generate artwork data having smaller line width successively.