日本的東海政策將對台灣的主權與主權權利造成明顯而立即的影響，因此，日本的東海政策值得深入研究，以維護國家海洋權益。 目前，日本與台灣、中國圍繞在東海的爭端，主要區分為以下三大部分。首先，海域爭端：日本與台灣、中國在東海出現了專屬經濟海域重疊狀況，引發海域劃界糾紛。其次，島嶼爭端：台灣、中國與日本皆主張擁有釣魚台列嶼的主權。第三、油氣爭端：台灣、中國、日本均面臨石油短缺問題，都很重視東海石油的開發與利用。所以，本文選定以日本對於東海的海域政策、釣魚台政策，以及油氣田政策三個息息相關且不可分割的海洋政策面向，來研究日本的東海政策。 本論文從歷史研究途徑的角度，輔以國際海洋法的觀點來探討日本的東海政策，共分為六章：第一章「緒論」說明研究背景、研究動機、研究目的、研究方法，與研究面向。第二章「東海的地緣環境」介紹東海的地緣範疇、經濟價值，與戰略地位。第三章「海域政策」探討日本在東海的海域政策，包括領海、專屬經濟海域、大陸礁層，並說明日本與中國的海域劃界主張。第四章「釣魚台政策」整理歷次釣魚台主權爭議的經緯，並論述爭端國各方主權主張的法理依據，然後指出日本對於釣魚台的政策實踐。第五章「油氣田政策」回顧周圍國家在東海的探採活動，其次討論春曉油氣田事件中，中國的探採經過與日本的因應對策，接著分析中日東海油氣田爭端造成的影響。第六章「結論」歸納主要論點，根據研究結果指出影響日本東海政策的國內外因素，以及日本的東海政策之特點，俾使台灣事先研擬相關對策，進而爭取最大之國家利益與海洋權益。 / Japan's East China Sea policy has a clear and present influence on Taiwan's sovereignty and sovereign rights. Therefore it is important for us to study Japan's East China Sea policy in order to protect our nation's sea rights and interests. At present, the main conflicts between Japan, China and Taiwan in the East China Sea are as follows: First, the maritime delimitation disputes between Japan, China and Taiwan in the East China Sea. Second, Japan, China and Taiwan all declared territorial sovereignty to Tiaoyutai Islands. Third, Japan, China and Taiwan all have oil shortage problems, so they pay much attention to the exploration and the use of petroleum in the East China Sea. Then this thesis selects Japan's sea policy, Tiaoyutai Islands policy, as well as oil and gas fields policy, three closely linked and inalienable sea policy dimensions, to study Japan's East China Sea policy. The thesis discusses Japan's East China Sea policy from the perspective of historical approach and international law of sea. There are six chapters in this thesis: Chapter One makes a description of the background of the study, the purpose of the study, the objective of study, the methodology of the study, and the dimensions of the study. Chapter Two gives an introduction to the East China Sea's surroundings, economic value and strategic position. Chapter Three probes Japan's sea policy, includes territorial sea, exclusive economic zone, continental shelf, and discusses the claims of the maritime delimitation made by Japan and China. Chapter four looks back on the sovereign dispute history of Tiaoyutai Islands, and exhausts the legal basis of the claims made by Japan, China and Taiwan, then points out the practices of Japan in Tiaoyutai Islands. Chapter Five reviews the exploration of the petroleum made by the countries situated around the East China Sea, then discusses China's exploration of Chunxiao oil and gas fields, and the countermeasures of Japan, then analyzes the impact of disputes between China and Japan in the East China Sea oil and gas fields. Chapter Six concludes the main issues, points out the domestic and foreign factors which affect Japan's East China Sea policy, and the characteristics of Japan's East China Sea policy. Thus Taiwan can plan the related countermeasures and strives for our national interests and the sea rights in the future.