In Japan, many local governments implement the various policies aiming at increase of interregional mobility, especially population mobility so called "Kouryujinkou", as it is believed that development of interregional linkage contributes to the regional economic growth. However, does the increase in such mobility lead to development of regional economy truly ? On this hypothesis, this paper clarifies definition interregional mobility as a local policy tool, and examines an effect of "industry for interregional service trade" on the regional economy. This paper is organized as follows; Initially, transition of a local policy is shown in terms of interregional linkage, and second "Kouryujinkou" is defined in economic points of view. Third, the new index is introduced as a policy tool available for both cross-section and time series analysis. Finally, We empirically examines an effects of factor mobility on the national and regional economic growth using Regional Input-Output Table and regional economic base model. Thereby, we verify that it is concluded that the proportion of industry for interregional service trade is expanded in Japanese economy and this industry leads growth of regional economy, and implies industrial promotion for a local policy. In this paper, it is assumed that the economic activity corresponding to non-goods demand by other regions is defined as the activity of "industry for interregional service trade".