64 วารสารสังคมศาสตร์ คณะรัฐศาสตร์ จุฬาฯ *Assistant Professor, School of International Affairs, Faculty of Political Science and Public Administration, Chiang Mai University, Huay Kaew Road, Muang, Chiang Mai 50200. Email: narut.c@cmu.ac.th **This work is supported by the Faculty of Political Science and Public Administration, Chiang Mai University. Received February 15, 2021; Revised May 6, 2021; Accepted December 23, 2021 Actors in Japan’s Political Economy and Their Roles in Policy Formulation on Connectivity in the Greater Mekong Subregion: A Theoretical Consideration** Narut Charoensri* Abstract This paper aims to analyze the ‘iron triangle’ concept which is used to explain Japan’s economic dynamics. However, the iron triangle concept has not been included in Japan’s foreign policy analysis systematically. This paper chooses Japan’s foreign policy towards international transport development in the Greater Mekong Subregion (GMS) as a case study because the GMS region has a significant number of Japanese investors. Japan’s government agencies and private companies have indicated their desire to see regional connectivity in the GMS region through mechanisms and organizations in various ways. Accordingly, researching into the desire of private companies in the GMS region, and the relations between the Liberal Democratic Party’s (LDP) politicians, bureaucrats, and the private sector would help us rethink the validity of iron triangle concept. At the same time, it would help us understand the relations between the iron triangle and Japan’s foreign policy formulation, thus indicating the pluralistic character of Japan’s foreign policy. The main research question of this article is: given ongoing economic and political changes in Japan, how do actors other than those in the iron triangle play roles in Japan’s foreign policy formulation. This article is divided into four main parts: (1) the debates on the iron triangle and Japan’s foreign policy; (2) analysis of actors in Japan’s political economy and its foreign policy; (3) Japan’s role in international transport development in the GMS; and (4) conclusion. Keywords: Japan, iron triangle, foreign policy, economic corridors, Greater Mekong Subregion (GMS) Journal of Social Sciences Faculty of Political Science Vol. 52 No.1 (2022): 64 - 88 Chulalongkorn University http://www.library.polsci.chula.ac.th/journal2