「政府開發援助」長期以來在日本對外關係的經營被視為是舉足輕重的政策工具。本研究認為「政府開發援助」在本質上牽涉到國家利益與國際公益的辯論，為了進一步分析日本援外政策在東南亞的實踐，本研究擬將國家利益與國際公益進行類型化分析，並且以「國家利益的在地化」作為研究途徑，觀察日本如何將國家利益發展成國際公益，並且透過國際公益的轉化，結合在地的國家利益，實施對外援助的兩階段過程。 本研究嘗試著將兩階段的過程對應到日本東南亞外交政策的發展脈絡上，發現日本的東南亞政策歷經「信任醞釀期」、「擴大合作期」與「深化協力期」三項主要轉折。從政策發展脈絡中，可以發現日本對於援外政策的理念驅動政策的變遷，不同時期的援外政策代表著不同的國家利益，而國家利益的形塑則來自於不同時期日本對東南亞的認識與關注。 在當前日本東南亞政策的討論中，本研究發現日本所組建的「日本-湄公協力」是一套以對話形塑理念的多邊機制。上述機制突破傳統以雙邊關係為基礎的援助關係，顯示日本逐漸採行區域開發的整體形式，將自身的外交作為與存在感融入區域開發議程中，進而強化日本、湄公區域乃至於東協十國的全方位連結。 本論文認為援助在日本的外交層面、貿易層面以及國家品牌的建構上，扮演至關重要的角色。從次區域的角度來看，跨域援助的實現是強化與東南亞交往的重要政策工具，不僅有助於日本建構區域論述權、持續主導區域開發議程，更能將區域的成長動能轉化為日本國內產業升級、培養高層人際網絡的政治資源。日本在亞洲所樹立的援助模式與轉型，尤其值得臺灣參考。 / Official Development Assistance (ODA) has been an important tool of Japan’s foreign policy. This thesis argues that ODA involves with the debate on national interests and international welfare. For observing the practice of Japan’s foreign aid in Southeast Asia, this research conducts classification analysis. First, national interests and international interests are defined respectively. Second, “localization of national interests” approach is used to observe the process in which national interests are transformed into international interests by integrating local concerns into the original targets. Two phases above correspond into the development of Japan’s Southeast Asia policy, which could be separated into three stages, including “trust-building stage”, “cooperation-enhancing stage” and “cooperation-deepening stage”. These policy variations are motivated by Japan’s concept on ODA, shaped by Japan’s perception towards Southeast Asia. Japan-Mekong Cooperation is a multilateral mechanism to shape shared idea through dialogues. The Japan-Mekong Cooperation suggests Japan’s holistic approach on regional development issues to increase its presence in the region. Furthermore, it could be a basis to strengthen the connections between Japan and ASEAN member states. Japan's ODA plays important roles in its diplomacy, trade and construction of Japan’s national brand. From sub-region perspective, Japan’s aid is also an important policy leverage to strengthen its relations with related states, to establish its discourse power in the region, and to upgrade Japanese domestic industries. Japan’s aid paradigm could be a useful experience for policy makers in Taiwan.