Ionene Polymers with N,N'-(p-phenylene)dibenzamide linkages were synthesized in high yields by the copolymerization of 1,4-bis[4-(chloromethyl)benzamide] benzene and alpha, omega-ditertiary amines in N,N-dimethylformamide. The ionene polymers provided physical hydrogels under ca. 1-5 wt % of the concentrations after heating and cooling at room temperature without any other additives. The gelation ability was dependent on the diamine spacers and/or the molecular weights, and the ionene polymer with the longest hexylene linker connecting ammonium cations was the most effective gelation capability in water among these ionene polymers. In the theological measurement, the hydrogel showed a unique thixotropic nature that was a fast self-recovering property after the continuous oscillatory shear stress. Furthermore, the ionene polymer has an additional function as a dispersant for single-walled carbon nanotubes (SWNT) in water.