Recently, components of automobiles and aircrafts have been required to be both lightweight and high strength in order to improve their dynamic performance and fuel efficiency. Therefore, in order to design lightweight and lean structures within the given design specifications, it is important to understand the characteristic in terms of structural property. By evaluating quantitatively the importance of load transfer in the structure, it is possible to use this information as a guideline evaluating the structure that satisfies the requirements of weight and strength simultaneously. In this study, we propose a new method to express the load transfer by defining the spring stiffness K and quantitatively calculating it. It represents the transition of stiffness in each part of the elastic structure. In this paper, the distribution of spring stiffness K is demonstrated by calculating for a flat plate and a perforated flat plate assuming mechanically equivalent simple tension, and is confirmed in the law of action-reaction as stress distribution.