Taiwan has many indigenous peoples since thousands years ago. Accompany with the external immigrant migrated into Taiwan, and established the political power; society also assimilated the culture of indigenous peoples in the same time. Through many hundred years, indigenous peoples lost their identity gradually. Many indigenous began to return their national consciousness until these resent thirty years. But the indigenous peoples who were assimilated seriously always met obstacles when they contact with the government. Does Country have power to decide groups of people are indigenous people or not? What are the regulation purposes when Country regulates who are the indigenous people and who are the members of indigenous people? This article compares with the degree of Ainu nation were assimilated, and how this people rehabilitated their right. This article finds the assimilation extent between Ainu and Plains indigenous people are very similar, and both of them have very strong culture identity. While Ainu were recognizes as an indigenous people by Japanese government in 2008, a lot of Plains indigenous peoples are still exerting. When we are thinking should Country need to help these peoples or not, the Japanese experience is worth us to consult. Siraya nation has all of the characteristics of indigenous people; government, base on multiple-culture, should recognize its indigenous status. Especially when other peoples argue its legitimacy, courts also have opportunity to make judgments. These judgments can correct the error when a group of people is not indigenous in the nature. Therefore, this article concludes we can accept notification system when we judge a group is indigenous or not. Besides, when we judge a person is an indigenous or not, we can use private regulation, indigenous people can make decisions by themselves.