The designs of structures, such as bodies of cars, hulls of ships, and frames of buildings, can be roughly divided into two flows: those are the upper flow and the lower flow of the design process. In this study, the new structural design method called “Robust Fail-safe Structural Design Method” is proposed for structures that are designed in the upper flow of the design process. By this method, the Young’s modulus and the topology of the structures are determined simultaneously. The designed structures also have the characteristics of robustness and fail-safe. The numerical example is shown to demonstrate to design a structure by this method. In the numerical example, some candidates of the robust fail-safe structures are derived and the problems are discussed.