Inkjet printing on the coated paper has been required for many years, but it is known that because of poor penetration ability of the coated paper, residual ink on the coated paper causes bad effects on print performance. To investigate the relationship between dispersion stability of ink and print quality, three types of dispersion were prepared (self-dispersed pigment type, surfactant-dispersed pigment type and polymer-dispersed pigment type). Ink with higher dispersion stability is less likely to aggregate during drying process, which leads to less roughness, high optical density, gloss and good abrasion resistance. When humectant in ink was optimized in terms of penetration into coated paper, polymer-dispersed pigment showed prominent print quality.