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.