A board design aiding apparatus that simplifies a designed printed wiring board to predict a displacement quantity of the printed wiring board includes a layer thickness calculation section 21 for obtaining a mean thickness of an area of a board by a prescribed rule for an essential material forming a layer at each layer for constructing the printed wiring board, and a laminate model forming section 22 for forming a simple laminate model by laminating layers having layer thickness calculated by the layer thickness calculation section 21.