A calculation method for static mechanical behavior of double wall type structure has not been established. In this paper, A numerical calculation method by stiffness matrix method is proposed to predict static mechanical behavior of double wall type structure. This proposed method applies theoretical equations that were obtained by Ohbori et al considering both the interaction between walls and filling material above ground and lateral resistance of walls under ground. Then, this method was considering elasto-plastic. behavior of filling sand and ground.The calculated results by this proposed method coincide well with the behavior of model structures in The paper of Ohbori et al. Furthermore, to apply this proposed method for design calculation and to evaluate the behavior of new type double wall structures, several double wall type structure models were calculated.