An aqueous ink is disclosed which comprises an emulsion of a polymeric dyestuff which is prepared by bonding a water-insoluble polymer containing amino groups with a dye selected from the group consisting of anion-type dyes and reactive dyes, which aqueous ink is free from globbing and skipping during writing and yields a high quality written image. When desired, a water-soluble viscosity-adjustment agent can also added to this aqueous ink. In this case, the viscosity of the aqueous ink can be adjusted to be in the range of 50 cps to 3000 cps and the ink is particularly suitable for use with a ball-point pen with a simple structure.