Extreme climate events such as typhoons, heat waves, and floods have increased in frequency with climate change. Many municipalities within the Republic of Korea (ROK) have experienced damage from these events, necessitating countermeasures. Vulnerability assessment has been suggested in the implementation of a national plan for reducing damage resulting from climate change. Thus, in this study, we assess the vulnerability of the ROK and identify key vulnerable municipalities in support of the national adaptation plan. We create a framework for assessing the vulnerability of all 232 municipalities of the ROK with respect to 32 items in 7 fields. The framework regards decision makersâ€™ comprehension and availability of data as important factors. We assess the vulnerability index of each municipality by using variables of climate exposure, sensitivity, and adaptation capacity. The weights of variables are determined by the Delphi method. We used the representative concentration pathways 8.5 climate scenario to reflect future climate exposure for the vulnerability assessment. From the analysis, vulnerability maps are prepared for the 32 items of 7 fields, and key vulnerable municipalities are identified by aggregating the maps. The distribution of vulnerable municipalities changes with the future climate conditions. These maps provide a scientific and objective basis for the ROK government to establish adaptation plans and allocate resources. The ROK government can utilize the results to identify the characteristics of highly vulnerable areas, and municipalities can use the results as a basis for requesting support from the national government.