Nutrition education in elementary school is confronted with the present problem, as a legal basis about obligation of nutrition education in school was clarified. Moreover, it's also important for providing evidence based scientific resources to make a study of evaluating the education effectiveness. Most studies of the nutrition education effectiveness have evaluated the changing dietary attitude and nutritional knowledge score before and after the nutrition education, and suggested the effectiveness of intervention as changing between pre- and post-treatment. Nutrition education, however, purposing long-term changes, follow-up evaluation process about the learned attitude and knowledge of nutrition education were requested. For these reasons, this study attempted to fulfilled standardized nutrition education program which use "Na Story and Food World" and "Na Story for Me", a textbook for the 1st-3rd grade and 4th-6th grade designed by KFDA, and analyzed the changes about the effectiveness of nutrition education happened over a period of time. In this study, each student was assessed their dietary attitude and nutritional knowledge by four periods, before the education, right after the education, after 3 months, and after 6 months. As a result, an average score of nutritional knowledge before the education, 70.08 +/- 17.91, were changed significantly higher right after the education to 85.69 +/- 15.05 (p < 0.001), but it lowered to 84 +/- 15.56 after 3 month. After the nutrition education, students in all grades had positive dietary attitude to Na reduction (p < 0.001). However, the healthy eating attitude about Na reduction had been unable to maintain after 3 and 6 months. Therefore, the systematic reeducated program in elementary school was positively necessary to reinforce children's learning and cognitive skills to maintain healthy eating knowledge and attitude toward Na reduction.