雖然「自決權」概念的發展甚早，然而至1966年《國際人權公約》通過以後，「自決權」始成為一種「權利」，具有法的地位與拘束力，亦成為當前解決國際爭端或民族糾紛最適切的手段。 在二十一世紀初的國際局勢中，運用自決權爭取「獨立建國」的案例很多，但成功的例子卻不多；究其原因，主要關鍵即在於是否具備「合法性」，亦即爭取自決獨立的民族是否具有正當性？是否有條約或法律依據？聯合國安理會與國際社會是否支持其獨立？這些皆為影響該民族行使自決權爭取「獨立建國」成功與否的重要因素。本論文中列舉東帝汶、科索沃與加拿大魁北克省獨立公投三種不同類型之國際案例，即可說明「合法性」實為「自決權行使」的主要根據。 本論文亦論及琉球獨立運動，筆者即由琉球獨立運動之正當性、國際法論據及其與自決權之關係加以闡述，並說明「合法性」與「爭取國際社會認同」始有助於琉球獨立運動之進行，藉以論述琉球獨立運動可行之方向。 本論文撰寫之主要目的，不在於鼓吹「爭取獨立之民族自決」，而在於建議「各國政府應該面對其國內民族問題，尋求和平理性的解決方案」；如此，始有助於國際間建構出和平與安全的法秩序社會。 Although the development of the concept of "the right to self-determination" is really early, but until "the International Covenants on Human Rights" have passed in 1966, and then "the right to self-determination" became one kind of "the right", and has the law status and the binding force. And now, "the right to self-determination" has become the most appropriate method to settle the international dispute or the national dispute. In the international situation of the 21st century''s beginning, there were many cases about exercising the right of self-determination to strive "be independent and found a nation", but successful example are not many. Looking into the causes, the most important point namely lies in whether to have "the legitimacy" or not. That is to say, whether the nationality that strives for the self-determined independence has the validity? Whether to have the treaty or legal basis? Whether the U.N. Security Council and international society support its independence or not? These all are important causes to affect the success or not that one nationality to exercise the right of self-determination to strive for "the independence and found a nation". In this thesis enumerates East Timor, Kosovo and the Canadian Quebec province independent referendum, three different types of the international cases to explain that "the legitimacy" is actually the main basis of "exercising the right to self-determination". This thesis also discusses the Ryukyu Islands independence movement. The writer elaborates it from the validity of the Ryukyu Islands independence movement, the international law argument, and the relation between the Ryukyu Islands independence movement and the right of self-determination. And also explains that "the legitimacy" and "striving for the international society to approve" only then has help for the advance to the Ryukyu Islands independence movement. So as to elaborates the feasible direction of the Ryukyu Islands independence movement. The main purpose of this thesis is not to promote "the national self-determination to strive for independence", but to suggest that "all countries'' governments should face its domestic national question, seek peaceful and rational solution", and it should be helpful to construct peaceful and safe law order society in the international world.