The age-related decline in adult skills in Korea is steeper than in major OECD countries. A regional analysis of this trend reveals significant disparities: compared to the Seoul Metropolitan Area, the decline is more pronounced in the Jeolla and Gangwon regions, whereas the Gyeongnam, Gyeongbuk, and Chungcheong regions exhibit a more moderate trend. These findings underscore the need for an in-depth assessment of how socioeconomic changes over the past decade have contributed to this decline in skills. They also call for the development of targeted policy strategies, from both labor market and social welfare perspectives, to mitigate regional disparities in skill depreciation.