UN Committee on the rights of persons with disabilities noted that the new adult guardianship system is substituted decision-making in korea, and recommended that the State party move from substitute decision-making to supported decision-making. To achieve the insight, the laws which is implemented for supported decision-making in five states of Canada are analysed comparatively. The notion of decision-making, legal capacity, and mental capacity are also reviewed. As a result of comparative analysis, though there are much similar point, there are also differences in entrance way into support relationship, the term and the role of decision making supporter, and the definition of decision making capacity. By this study, we can find it necessary to use minimally the current guardianship system and to create the various supported decision-making system. It is also necessary for capacity assessor to assess the mental capacity, and also necessary to support and monitor the decision making supporter.