Population Aging and Pension Sustainability Pressure in South Korea

South Korea is one of the fastest-aging societies in the world, and this demographic transition creates structural pressure on the long-term sustainability of the National Pension System. This paper analyzes South Korea's old-age dependency ratio (OADR) from 1960 to 2070 using population projection data from KOSIS and then reinterprets pension pressure through E-OADR, a supplementary indicator that considers the actual contribution base rather than the working-age population alone. The analysis shows that South Korea's OADR increased from 5.3% in 1960 to 25.8% in 2023 and is projected to reach 38.0% in 2030, 51.9% in 2040, 77.3% in 2050, and above 100% by 2070. This change places dual pressure on the pension system: the number of potential beneficiaries rises while the contribution base becomes relatively weaker and more uneven. E-OADR provides a more realistic view of this pressure by showing that actual pension burdens may be concentrated on a narrower group of contributors. Therefore, policy responses should not rely only on long-term fertility recovery. They should also strengthen contribution continuity among women, older workers, younger workers, and non-standard workers while gradually adjusting contribution rates, eligibility ages, productivity, and multi-layered retirement income structures.