The school-age period is significant in children's growth process. Children lacking self-management ability require regular support from their surroundings. In particular, educational institutions play an important part, and a health management system based on periodic medical examination is required. In this study, to develop a health management system, a health management process was visualized. In the next step, we developed a problem-finding method. Based on transition in height and weight, we developed a logic for early detection of children with a tendency toward short stature, overweight, and underweight. Additionally, we designed a support tool integrating this logic. The validity and feasibility were confirmed by a specialist by applying this method to actual body measurement data. Finally, we developed a structure of knowledge for cause analysis. For further study, feedback to children and their parents is required to enhance their self-care ability. In addition, it is possible to develop this into a regional health care system for individuals other than children by applying the methodology of regional cooperation.