The present invention provides an ultrafine barium sulfate particle, which improves, even if the particle is mixed in a water-borne composition, such as a water-borne coating composition or a water-borne ink composition, color saturation and gloss of color pigments, such as carbon black, or improve orientation of aluminum flakes or pearl pigments, which have been used in metallic coating compositions. The present invention also provides a water-borne coating composition and a water-borne ink composition, which contain the ultrafine barium sulfate particle. The present invention provides an ultrafine barium sulfate particle, comprising barium sulfate; and (1) a hydroxide and/or an oxide of at least one metallic element selected from the group consisting of Al, Si and Zr; and/or (2) a phosphate of at least one metallic element selected from the group consisting of Mg, Ca, Sr and Ba; the barium sulfate being coated with the hydroxide and/or oxide (1) and/or the phosphate (2).