An information processing device includes a computation unit that minimizes a difference between an observed displacement and an estimated displacement of an elastic body so as to find an optimal solution that determines a magnitude of an external force that acts upon an observed manipulation point and a distribution of an elastic modulus in a three-dimensional model of the elastic body, wherein the observed displacement is that acquired from an observed part of the elastic body in an image, and the estimated displacement is that acquired from a region of the three-dimensional model of the elastic body which has been captured, the region corresponding to the observed part.
