This paper discusses a shaping strategy of a rheological object whose deformation characteristic includes both elasticity and plasticity. We first introduce a seven-nodes viscoelastic model for approximating the outline and the dynamic characteristics of the object. Then, we show a shaping method of the object's outline, where the ratio between the object's length in the grasping direction and that in the perpendicular one is controlled by using a parallel jaw gripper. Based on the plastic deformation distribution for the integrated input stress, the proposed method can actively manage the final object's outline. In addition to the contribution on simplifying the gripper's degree of freedom, this method has the advantage that the handling time is drastically reduced, compared with the position based passive method. We finally show the experimental results for confirming the validity of the proposed method.