In design, simple model is frequently used but this has not been done for “combination-system”. Thus, this paper proposes a method to create an equivalent shear spring model of “combination-system” consisting of its characteristic values, dampers and their support members, and frames. The parameters for the model are calculated by conducting static analysis of the building frame in four states (i.e. states N, R, pN and pR). These parameters are vital to evaluate the seismic control effect of the “combination-system”. This paper shows that the proposed model reproduces the results of time-history analysis of member models.