A decoupling capacitor pin position information obtain unit calculates based on board design data of a printed board, position information indicating positions of decoupling capacitors on the printed board. A power supply plane position/shape information obtain unit calculates based on the board design data, position/shape information indicating a position and shape of a power supply plane of the printed board. A restriction condition input unit collects restriction conditions from an input device. A decoupling capacitor examination unit judges based on the position information, the position/shape information and the restriction conditions, whether or not arrangement of the decoupling capacitors is adequate. Therefore, a designer, while designing arrangement/wiring of the printed board, can check in real time whether or not the arrangement of the decoupling capacitors is adequate, and thus can design at higher speed a printed board in which arrangement of decoupling capacitors is adequate.