This study was conducted to investigate the effects of 10-week dietary education on elementary students in an after-school program in Seoul. Participants were 20 1-2 grade students and 283-6 grade students, and the dietary program consisted of dietary education and activities focused on children’s levels of understanding. The results were as follows: Total participant’s food habit scores and nutrition knowledge significantly increased (p<0.05) after dietary education. Food habit and nutrition knowledge scores of lower grade participants (grade) increased desirably (p<0.05). Meanwhile higher grade participants’ (grade) food habit scores also changed (p<0.05), but their nutrition knowledge scores were changed. Boy’s food habit scores significantly changed (p<0.05), whereas girl’s food habit scores did not change significantly. Further, female participants’ nutrition knowledge scores did not changesignificantly after education. Participants’ obesity knowledge scores significantly changed after the education (p<0.05), but their attitudes on obesity increased insignificantly. Lower grade participants’ attitudes on obesity significantly and desirably changed (p<0.05), whereas higher grade participants’ attitudes on obesity changed insignificantly. Girl’s knowledge and attitudes on obesity significantly and desirably changed (p<0.05-0.01). This study revealed the correlation between food habit scores and attitudes on obesity (p<0.01), demonstrating that participants with high food habit scores have advisable attitudes on obesity. The result of this study shows that lower grade participants’ food habit scores, nutrition knowledge, and attitudes on obesity changed desirably after dietary education. Therefore, this study promote the development of adequate nutrition education and materials focused on lower grade students and the need for systematic and continuous dietary education programs based on elementary school.