A method of producing surface-treated barium sulfate is disclosed which has an improved dispersibility in resins and coating compositions. The method comprises adding an aqueous solution of an alkali silicate to an aqueous slurry of barium sulfate which contains barium ion in excess to deposit barium silicate on the surface of barium sulfate, and then adding to the slurry a mineral acid to decompose the barium silicate to hydrous silica. The thus surface-treated barium sulfate may be further coated with hydrous metal oxides such as alumina or with a silane coupling agent so as to have a more improved dispersibility.