An ink composition includes a self-dispersible coloring agent that includes an ionic group and a non-ionic linear or cyclic ester or amide moiety on a surface of the coloring agent at a mole ratio of about 1:10 to about 10:1, an organic solvent, and water. The coloring agent has a modified surface, so that stability of the ink can be increased due to an interaction between the coloring agent and the organic solvent, the particle size of the coloring agent can be kept uniform, an adhering force with respect to a substrate is increased to minimize bleeding between colors of a printed image, waterfastness and rubfastness in dry and wet conditions are increased to obtain an excellent colorfastness, and resulting in a high quality printed image and an excellent storage stability.