To provide an analyzing method for a composite membrane structure which is capable of simulation analysis with accuracy taking buckling into consideration even in large deformation, in analysis of the composite membrane based on a finite element method.

With this analyzing method for the composite membrane structure by analyzing the composite membrane structure in which an elastic body is reinforced by a reinforcing cord by the finite element method, the composite membrane structure is modeled, a vertical elastic coefficient of the reinforcing cord is set according to a value of distortion of the reinforcing cord, a load condition acting on the composite membrane structure is set, the distortion of the reinforcing cord in each of solid elements constituting the composite membrane structure is calculated under the set load condition, it is determined whether the calculated distortion is tensile distortion or compression distortion, the vertical elastic coefficient corresponding to each of them is chosen, a stress acting on the reinforcing cord is calculated using the chosen vertical elastic coefficient, and the stress acting on the solid element and the stress acting on the reinforcing cord are added.