To provide a designing method which can design an optimum shape in a short time, a structure analyzing device which is used for the designing method, and a design support system which is used for the designing method.

A flywheel housing is modeled together with an adjacently coupled clutch housing and a transmission case, modeling inputs are analyzed by the structure analyzing device 18, and the analysis results obtained from the models are compared to determine an optimum design shape. The parts of the clutch housing and transmission case are modeled with cylindrical shapes as simple shapes and modeling inputs of the same cylindrical shapes are used to perform the modeling input of flywheel housings in different shapes, thereby analyzing them.