In this article, we reviewed the transition of designing structure and business content in Japanese electric manufacturers, and simultaneously examined the issue of considerable design management (design decision-making) with the change at the present time. As the result, for two companies that we researched with a preparation of map of design domain, we found that those companies have concentrated on so-called a traditional design work (modeling/direction of concept embodiment) and a development (design) was their main business area among the product development processes during 1970's, but they expanded their business area to both upstream and downstream for product development process while the time has passed to 1980's, 1990's, and 2000's. (Especially the expansion for initial stage of upstream was larger) Furthermore, it was characterized as a conceptual portion for technological area or a level of involvement for initial stage of technological area was principally increased. By expanding the design business area to upstream and downstream of product design development, for a design management issue led by trend of commoditizing mainly for ICT products and particularly a design decision-making issue among other things, we pointed out that early design decision-making was related to early issue finding and solution, and it would not only accelerate management decision, but also contribute for shortening of product development period and product quality improvement.