The economic of a country development rely on the growth of the international business, to promote MNE international industry competitiveness in order to expand the international competitiveness of home industries. MNE adopts "The strategy of the effect of intra-firm trade", regardless of "effect of replacement export" "effect of adverse import" and "effect of lead export" all belong to the total sale amount of MNEs' home companies and subsidiaries. Not only the reinforcement of the "effect of replacement export" can increase the "effect of lead export" of home countries, but also the host countries can expand the "effect of adverse import" to home countries. Thus, this study is taking the example of Japanese MNE, in comparison between the year 2000 and the year 1990 to discuss the influences on international industry competitiveness of both home countries and host countries to the "effect of intra-firm trade" of MNE in terms of the outward investment data from Ministry of Economic Affairs, Japan. This study suggested that Japanese MNE has overcome the threats under Section 301 of the Trade Act of the US with great exertion to develop the sale of American market has reached the rate of 90%. Regardless of buying and selling are host countries and EU which is the way that EU using the feature of market. The total sale amount of export in Japan has reached its twice because of MNE manufacturing industry reinforces the "effect of replacement export", which expands the "effect of lead export" to home countries. Thus, in order to understand the economic development of Japan, the international competitiveness of home industry and the international competitiveness of MNE should be taken into account. Due to the investment changed from MNE to host countries, such as Taiwan, Korea and China, which helps technology transfer, the "effect of replacement export" as well as the "effect of adverse import" to home countries. Besides, the export back to Japan has reached four times in its development. The international competitiveness of Chinese industry to Japanese market is higher than Taiwan and Korea, thus, the top 5 products of these countries in Japanese market can get high international competitiveness.
