This paper analyzes from a viewpoint of a regional factor about the background of the location and accumulation of the information service industry in Japan. Although the information policy aiming at regional economy and industrial gap correction has been performed in Japan after the 1980s, the information service industry is located in Tokyo extremely. It becomes clear that a demand factor and the information factor in economy have influence to the location and accumulation of this industry as a result of the analysis in this paper. Especially for large scale establishments, the information progress in the area has big influence. On the other hand, while the location and accumulation of this industry is competing with other industries, it also becomes clear that the grade of competition changes with enterprise scale.