A printed circuit wiring board designing support device includes a layout
data receiving section receiving printed circuit board layout data
through an input/output section, a section for extracting structures of
power supply/ground planes, a via hole extracting section for extracting
a via hole interconnecting the wirings extending over power supply/ground
planes, a capacitor extracting section for extracting a capacitor
connected between power supply/ground planes, a distance measuring
section for measuring the distance between the via hole and the
capacitor, a database where the allowable distance value between the via
hole and the capacitor in respect to the distance between the power
supply and ground planes is recorded, an examination section for
comparing the capacitor/via hole distance with the allowable distance
value, and a warning section for issuing a warning when the distance
between the via hole and the capacitor is larger than the allowable
distance value.