Abstract: Polymeric compounds suitable for ink and toner compositions, and image forming methods and apparatus using an ink or toner composition containing such a polymer compound, and particularly to a polymer compound having a repeating unit structure represented by the general formula wherein B is a linear or branched alkylene group having 1 to 15 carbon atoms and may be substituted, m is an integer of 1 to 30, q is an integer of 2 to 30, and R1 is hydrogen, an alkyl group which may be substituted, or an aromatic ring structure which may be substituted, with the proviso that when m is a plural number, the B groups may be different from each other, ink and toner compositions containing the polymer compound, a solvent or dispersion medium and a coloring material, and image forming methods and image forming apparatus using such a composition.