It is well established that excessive sodium intake is related to a higher incidence of chronic diseases such as hypertension, stroke, coronary heart disease, cardiovascular disease and gastric cancer. Although the upper limit of the current sodium intake guideline by WHO is set at 2,000 mg/day for adults, sodium intake of Koreans is well over 4,700 mg/capita/day implying an urgent need to develop and implement sodium intake reduction policy at the national level. This study investigated the cost-effectiveness of the sodium intake reduction policy, for the first time, in Korea. Analyses were performed using most recent and representative data on national health insurance statistics, healthcare utilization, employment information, disease morbidity/mortality, etc. The socioeconomic benefits of the policy, resulting from reduced morbidity of those relevant diseases, included lower medical expenditures, transportation costs, caregiver cost for inpatients and income losses. The socioeconomic benefits from diminished mortality included reductions in earning losses and welfare losses caused by early deaths. It is estimated that the amount of total benefits of reducing sodium intake from 4.7 g to 3.0 g is 12.6 trillion Korean Won; and the size of its cost is 149 billion Won. Assuming that the effect of sodium intake reduction would become gradually evident over a 5-year period, the implied rate of average return to the sodium reduction policy is 7,790% for the following 25 years, suggesting a very high cost-effectiveness. Accordingly, development and implementation of a mid-to-long term plan for a consistent sodium intake reduction policy is extremely beneficial and well warranted.