PURPOSE: To reduce the number of pins to be connected that cannot be connected and to reduce an influence of the interference of wiring patterns on computer operation.

CONSTITUTION: A processing box 1-1 determines the minimum rectangular area that includes outer contours of parts to be laid out. A processing box 1-2 determines an area on a printed wiring board for fabricating parts. A processing box 1-3 determines a vacant area in the printed wiring board from a total of summing up the minimum rectangular area for every part and an area in the board available for fabricating parts. A processing box 1-4 figures out areas that are reserved in advance around parts for wiring. A processing box 1-5 lays out reserved wiring areas for parts so as not to overlap one another. A processing box 1-7, when there remain unlaid parts, contracts wiring areas reserved around parts to relay out reserved wiring areas.