The aim of this study was to estimate the economic value of the Paldang dam for its function against climate change. We utilized the choice experiment method with three attributes such as drought protection (DP), flood prevention (FP), and water purification (WP), all of which were determined at three levels: status quo, partial improvement, and full improvement. From the survey data from 1,096 households living in the Seoul, Gyeonggi and Incheon Metropolitan Areas, 6,576 responses were used in the model estimation. The main results derived from a conditional logit model demonstrated that a larger willingness to pay (WTP) for improvements of the functions of the Paldang dam was associated with a higher level of the DP, FP and WP functions. The marginal WTP for DP, FP, and WP were respectively computed as 4,165 KRW, 1,583 KRW, and 12,003 KRW. Consequently, the total value of commonweal function was calculated as 17,751 KRW.