This study examined the effects of a nutrition education program on nutrition-related knowledge, eating habits, and dietary behavior. Subjects were 3rd grade elementary school students in Anyang, Gyeonggi-do. A 5-week nutrition education program was implemented to 28 children and another 26 children were included in the study as a control group. A self-administered questionnaire was used to assess the effects of nutrition education program. Mean nutrition related knowledge score was improved after education (p < 0.001). There was a significant improvement in knowledge of nutrient source (p < 0.05), role of protein (p < 0.05), food tower (p < 0.001), getting information from nutrition labeling (p < 0.05), and proper way of snacking (p < 0.001). Eating habits and self-efficacy also tended to improve by nutrition education, especially eating habit of snack and self-efficacy on balanced diet reached significant improvement (p < 0.05). Food consumption frequency was not changed significantly, only consumption of sea weeds which is considered as a reluctant food among children was increased after education (p < 0.05). In addition, the number of leftover food items and total amount of leftover at school lunch reduced significantly after education when compared with the same 10-day menu prior to education (p < 0.01). This result suggests that unbalanced dietary behavior has been changed with the nutrition education program. In conclusion, the nutrition education program was found to be effective in improving nutrition-related knowledge, eating habits, and dietary behavior.