Tailored nutritional education is generally found to be more effective in changing behaviors and to be more fully implemented than a non-tailored equivalent. This study was conducted in order to develop tailored nutritional education materials on food additives in processed foods based on need and levels of knowledge of educational targets of elementary-school students in Seoul Metropolitan City. The focus group interview was conducted with six elementary-school nutrition teachers in order to gather information and to develop a tailored quantitative questionnaire for the survey. Based on the results from 138 nutrition teachers, all answered that education on food additives in processed foods for students is necessary and both teachers and students need to receive education regarding definition, safety, and use of food additives for each processed food, in the form of video, PPT, and teaching-learning plan. Nutritional education materials for two classes were developed using video clips (grocery shopping and cooking class) about food additives in processed foods, PPTs with activity papers, two teaching-learning plans, and school newsletters to parents. In conclusion, the current study warrants conduct of further studies short-term and long-term impacts and efficacy of tailored need-based nutrition education in promotion of healthy nutrition by conveying proper scientific knowledge regarding food additives in processed foods for elementary-school students.