Abstract This paper describes the design of Health Monitoring Seat System, a safety device that prevents health related traffic accidents. The current system can only prevent drowsy driving, and cannot consider individual differences. Therefore, the purpose of this study is to design a new system that optimizes to an individual, and provides functions that work towards the driver's health condition. To realize this system, the Timeaxis Design, a concept incorporating the viewpoint of time into the theory and methodology of design, is introduced. The perspective of Timeaxis Design, enables the design of a system undergoing several development stages necessary for realizing this system. The system undergoes three development stages: STAGE I (existing technologies), STAGE II (developing technologies), and STAGE III (conceptual technologies). In order to design the system, the driver's physical and psychological health conditions must be put into concern. Therefore, the M Method and SysML is used in the designing process. The M Method is a design method that can describe the relationship of the physical and psychological element of a human. The SysML is a graphical modeling language that visualizes the development process of a system. As a result, three subsystems: “Data analysis system”, “Monitoring system”, and “Seat system” that construct this system are proposed. Furthermore, by considering the Timeaxis Design, the road map for the technological development of this system is derived.