A computer readable storage medium storing an electromagnetic field simulation program that causes a computer to execute receiving data defining, in virtual space, a shape of a conductor and an insulator included in a conductive layer and a dielectric layer of a printed circuit board; setting a plurality of cells in the virtual space by arranging nodes of the cells on a boundary between the conductive layer and the dielectric layer in a thickness direction of the printed circuit board and by arranging nodes of the cells at regular intervals in a plane parallel to the printed circuit board; giving, to each of the cells, an electric constant of a medium occupying an area of each of the cells; and determining a change over time in a an electromagnetic field strength in each of the cells.