To analyze vibration of a frame mechanism formed of a top plate having a driving machine requiring positioning and a flexible leg section for supporting the top plate at a less calculation amount and at an analysis accuracy equivalent to a finite element method of producing the strict solution as much as possible by input of the necessary minimum parameters, in which everyone does not rely on the experience or intuition.

The natural frequency of the frame mechanism 13 is calculated using, as input parameters, the width of the leg section 10 constituting the frame mechanism 13, the depth of the leg section 10, the height of the leg section 10, the material characteristic of the leg 10a constituting the leg section 10, the cross-section shape characteristic of the leg 10a, the mass of the top plate 12 supported by the leg 10a, and the mass of the machine 11 on the top plate 12. In other words, because the rigidity of the leg 10a significantly contributes to reduce the error between the model and the actual machine even when the top plate 12 is considered as a rigid body, the natural frequency of the frame mechanism 13 is calculated with small number of input parameters by using a model of sufficiently increasing the rigidity of the top plate 12 compared with the leg 10a and neglecting the influence of the top plate 12.