1. A method of calculating a predictive shape of a wire structure, comprising: providing a finite element model of the wire structure, the finite element model being formed as an elastic body having a plurality of linearity beam elements combined at respective joints; setting physical properties, restriction conditions and loads of the wire structure to the finite element model; calculating a predictive shape of the finite element model which is in a physically balanced condition based on the physical properties, the restriction conditions and the loads; outputting the predictive shape of the finite element model; calculating the loads which are applied to the respective joints of the finite element model at the predictive shape; and displacing a predetermined control point on the finite element model, wherein the predictive shape of the finite element model, in which the control point is displaced, is calculated based on the loads applied to the finite element model prior to the displacement of the control point in the predictive shape calculating process.