To provide aqueous pigment ink that has good color development and ink absorption, and can enhance abrasion resistance in an image portion and correspond to high speed in printing, when forming a full color image on a variety of printing mediums by the use of the aqueous pigment ink.

This ink for use in ink jet printing comprises at least water, a water-soluble organic solvent, pigment and a dispersant, wherein it is characterized in that (1) mean particle size of the pigment dispersed in the ink is in a range of 50 to 100 nm and the dispersed pigment of 50% or more in the distribution of particle size exists in a range of 50 to 150 nm, and (2) the dispersant exists in the ink at the ratio of 5 to 50% based on the total weight of the pigment.