This study was performed to evaluate economic effect of the water fluoridation program in Cheong-Ju City from 1982 to 2010. To study this economic effect, this study used cost-benefit analysis methodology from eight years old to fourteen years old in Cheong-Ju City. Major findings were as follows; First, total cost of fluoridation program in Cheong-Ju City was 1,384,164,734 korean won and total benefit was 15,057,426,621 Korean won from 1982 to 2010. Second, total cost which was converted by present value 2000 year was 1,687,412,718 won and total benefit which was converted by present value 2000 year was 14,582,548,519 Korean won. Cost-benefit ratio was 8.64. Net present value which happened from 1982 to 2000 was 7,990,710,155 Korean won and cost benefit ratio was 7.47. In conclusion, by the above result, economic impact of the water fluoridation program was very effective for children in some area of Cheong-Ju city.