We have examined control of the polymer melts and solutions in order to improve the processability of polymers. The polymer melt rheology is used to describe the physical properties of a polymeric material so that we know what to expect when the polymer is processed by a certain method such as injection molding, film (or sheet) extruding, coextruding, blow molding and fiber spinning. The two basic flows, that is, shear and elongational flows are used to characterize polymers. Although the shear flow behavior is common, is sometimes insufficient for the processings to provide a complete picture of the relationship between the processability and the flow behavior when underwent free-surface processes in which the shape and thickness of the extrudate depend on the rheological properties of the melt. Therefore, we have focused attention on the melt rheology (especially elongational behavior) control to enhance the processability. I will present the results on the rheology control and the enhanced processability.