1. A three-dimensional object processing device for executing processing for deforming a three-dimensional object that is disposed in a virtual three-dimensional space, comprising: an instruction receiving unit configured to receive a plurality of deformation instructions which are provided in the virtual three-dimensional space for the three-dimensional object from a user, wherein each deformation instruction includes a fixed point on a surface of the three-dimensional object which is a point not to be moved, a deformation point which is a position of which is to be changed from among vertices of a plurality of surface elements constituting the surface of the three-dimensional object, and a direction and an amount of change of the position of the deformation point in the virtual three-dimensional space, wherein the deformation instructions are only received in the virtual three-dimensional space; a projection unit configured to project the three-dimensional object onto a plurality of intersecting projection planes that are set in the virtual three-dimensional space to obtain a plurality of projected objects and to project the deformation instructions onto the plurality of intersecting projection planes; a projected object deformation unit configured to deform each of the projected objects that are obtained by projecting the three-dimensional object onto each of the plurality of intersecting projection planes in a corresponding one of the plurality of intersecting projection planes, wherein the projected object deformation unit deforms the projected objects using a corresponding projected deformation instruction and a 2D deformation algorithm in each of the plurality of intersecting projection planes; and a three-dimensional object deformation unit configured to combine the deformed projected objects to determine and display a shape of the three-dimensional object after the deformation.