This thesis aims at analyzing the relationship between the guardianships of R.O.C. Civil Code and Mental Health Act, and proposing suggestions for incumbent legal systems via comparative studies. It attempts to answer the following vexing question: how to apply law if a person, who lacks adequate capacity, fits in with both the definitions of “severe patient (Article 3 of Mental Health Act)” and “person under guardianship (Article 14 of Civil Code)”? At present, there are no instructions under current law and relative studies are surprisingly few. Firstly, recent international conventions have been repeatedly addressing the rights of people with disabilities. Instead of merely providing protection, it is more pivotal to help them make the best of their lives on their own. We must respect their roles as the master of their lives, and assist them to attend social activities with residual capacities. Symptoms of mental health disorders sometimes are considerably variant, and some of their causes still remain as myths until now. Also, support and companion from families and communities are greatly significant for patients’ recoveries. Therefore, as for policy-making, we should take patients’ supporting systems into account. Only by this method can we substantially lighten the burdens of family members and facilitate patients’ rehabilitation. In the second place, through understanding the transformation of psychiatry developments dated back from Japanese-ruled period, we can comprehensively analyze the pros and cons of related policies. Although Taiwan has increasingly invested in professional personnel and social welfare resources, we are still far behind from the goal of “normalization” which has been strongly advocated by international conventions. On the other hand, after comparing current frameworks of guardianships between Civil Code and Mental Health Act, we can conclude that both systems are established to protect and reinforce the interests for those who lack capacity, and also act as their representative to make or receive the expression of intent. Separated from the duties of guardians under Civil Code, the guardian of Mental Health Act is literally in charge of mental health affairs. Nonetheless, Mental Health Act is far less comprehensive than Civil Code. It lacks complete consideration for patients’ best interests and even permits some mandatory actions against their wills. Most importantly, there are no objective supervisory entities under the Act. As to the guardianship under Civil Cede, despite the modification in 2008, its contents are still shadowed by paternalism. The system is not only deficient in respect for people’s residual capacity, but also regulate too little over body-caring affairs (which leads to numerous subsidiary regulations). As a whole, under current legal structures, Taiwan still treats those who lack capacity as an object of protection. Regarding the application of Civil Code and Mental Health Act, Japan and UK has developed their own models. For Japan, challenged by severe impacts of aging population and low birth rates as Taiwan, has revised its civil law. On the other hand, like Taiwan, its guardians under mental health regulations are mainly responsible of medication and hospitalization assistance. However, the mental health guardianship has long been criticized in Japan, since it fails to respond to the changes in population trends, and enable government to get away from its duty. Therefore, Japan has announced the abolishment of this structure in April 2014. On the contrary, UK took another approach by embodying the spirits of “parens patriae”. It has delicate regulations over the definition and application of “best interests”, while examines strictly about the restrictions of one’s liberty. Besides, regarding mental health issues, UK has adopted the role of “approved mental health professionals”, who are certified with adequate ability and knowledge, to shoulder the similar responsibility of mental health guardians in both Taiwan and Japan. Separating mental health parts from body-caring affairs is actually worthy of debates. First of all, if the mental health guardian doesn’t necessarily serve as the legal representative, we should not grant him/her the limitless power as conferred by Mental Health Act. Secondly, current Mental Health Law is materially incomplete in various parts. Last but not least, people cannot seek remedies from any supervisory entity concerning mental health guardianships. Generally speaking, this thesis proposes the abolishment of mental health guardianships and the modification to the definition of severe patients. The civil guardian should take charge instead. Furthermore, once the patient is diagnosed as “severe patient”, hospitals are obliged to file for the application of guardianships. Prior to the decision made by court, family members should act us temporary guardian and the contact person. Thus, we can prevent the dilemma and potential problems caused by these two regulations, and defend the legal rights and best interests for those in need.