This study discusses the possibilities of Korean public guardianship services being redefined as a supported decision-making system. In Korea, as soon as the new adult guardianship system came into force on July 1, 2013, public guardianship services began to be provided for persons with developmental disabilities; those services are now also being provided for persons with mental illness and persons with dementia. Public guardianship services focus on the protection of personal affairs rather than financial management of persons under guardianship. This paper deals with the structure and operation of the public guardianship system for the rights protection of persons with developmental disabilities. The research revealed tasks that should be included in future public guardianship services, along with several points for improvement of the public guardianship system of Korea, as follows. First, the largest part of the service that public guardians will provide should be the protection of personal affairs, but financial management is also often included. Second, to relieve many guardians of complaints and difficulties they have faced in relation to dealing with institutions such as local authorities, banks, and courts, a central supportive organization should be introduced. Third, public guardianship services of Korea should be provided by guardianship corporations rather than individual citizen guardians. On the basis of such improvements, public guardianship services can be utilized as a supported decision- aking system in Korea where no other supported decision-making scheme has been provided.