A tank apparatus and a system for dispersing by circulating a mixture that prevents powdery additives from adhering to an inner face of a tank from scattering in the tank, from drifting on the surface of a liquid, and from agglutinating, are presented. The tank apparatus that stores a raw material that is slurry or liquid and supplies powdery additives to the raw material to mix them with the raw material comprises a tank for storing the raw material and a screw-type device for supplying powdery additives that is integral with the tank and supplies the powdery additives to the raw material in the tank, wherein a tip of a part for supplying powdery additives of the screw-type device for supplying powdery additives is inserted into the mixture in the tank.