In Internal Analysis Space analysis, assuming that no structural body and the like are placed outside of a conversion surface, an electromagnetic field distribution u0 inside of a conversion surface, on a conversion surface, and close to the outside of the conversion surface is found. In External Analysis Space analysis, on the assumption that there exists a structural body and the like outside of the conversion surface, an entire electromagnetic field distribution u is found. At this time, for the inside of the closed surface, an electric field distribution, where a differential electromagnetic field distribution e between electromagnetic field distribution u0 and electromagnetic field distribution u on the closed surface is a wave source, is found. Also at this time, for the outside of the closed surface, an electromagnetic field distribution, obtained by synthesizing electromagnetic field distribution u0 and electromagnetic field distribution e on the closed surface is found.