As the importance of protected areas has increased over the world, the 10th Convention on Biological Diversity (CBD COP10) suggested that at least 17 percent of terrestrial and inland water areas and 10 percent of coastal and marine areas should be conserved by 2020. In this regard, each country has been establishing the expansion and reinforcement of their protected areas. Currently, protected areas in the Republic of Korea that are designated and managed by ten legislations cover 14,177.9km2. Among these, excluding the duplicated areas, terrestrial protected areas occupy 11.2 percent (11,175.7 km2) of the total land area. These figures are lower than the suggested protected areas by CBD, lacking 5.8 percent (5,787.4 km2) compared to the figures suggested by CBD. However, since the way to expand protected areas by designating new protected areas is difficult in the reality, it is suggested that protected areas that are designated by national legislations able to be accepted at global level be newly designated as protected areas. Therefore, this study aimed to designate newly protected areas; areas within domestic land regulation under definitions and categories of IUCN protected areas, which are prohibited to develop consisting outstanding natural environment, natural landscape, and cultural landscape. As a result, the following areas were selected as newly protected areas; natural reservation area in the Natural Environment Conservation Act, mountainous districts for public interests in the Mountainous Districts Management Act, uninhabited islands under absolute conservation in the Act on the Conservation and Management of Inhibited Islands, traditional temple preservation area in the Korean Traditional Temples Preservation and Support Act, absolute conservation zone in the Special Act on the Establishment of Jeju Special Self-Governing Province and the Development of Free International City. By including such areas, the legal terrestrial protected areas will occupy 21.2% (21,128.1 km2) of the total land area. Including the national legal protected area into the international natural protected areas’ categories is more realistic and efficient than designating new protected areas. This result will play a significant role in implementation of protected area expansion suggested by CBD for the future, serving as current data of national protected areas.