The present invention relates to ink jet printing ink consisting of an independently dispersed metal ultrafine particles-containing liquid dispersion in which the metal ultrafine particles having a particle size of not more than 100 nm are independently and uniformly dispersed and which is excellent in characteristic properties required for ink. The ink is used in the printing or the formation of conductive circuits using an ink jet printer. The ink can be prepared by steps comprising the first step in which metal vapor is brought into contact with vapor of the first solvent according to the evaporation-in-gas technique to thus form a metal ultrafine particles-containing liquid dispersion; the second step in which a low molecular weight polar solvent as the second solvent is added to the liquid dispersion to thus precipitate the metal ultrafine particles and to extract and remove the first solvent; and the third step in which the third solvent is added to the resulting precipitates to carry out solvent-substitution and to thus give a liquid dispersion containing metal ultrafine particles independently and uniformly dispersed therein, a dispersant being added in the first step and/or the third step.