Polymers are very useful to improve the print durability and already used in many printing systems such as electrophotography. It relies mainly on the property that polymers can make a film to fix the colorants on the media. And polymers are also very useful to control the flow property of the ink fluid. For applying these properties to the ink jet system, the combination of polymer emulsion colorant and appropriate polymeric additives is thought to be efficient. This work was undertaken to study the ability of polymeric additives in the pigment contained polymer emulsion based ink to improve the jetting phenomena holding good print reliability and durability. Several kinds of water-soluble polymer such as polyether, polyamide, polyelecrolyte were added to the pigment contained polymer emulsion based ink, and the change of physical properties of ink was investigated. It was shown experimentally that polyamide and polyethylenglycol derivatives were useful to reduce the kogation and to elevate the drop velocity without deterioration of the print durability.