Abstract: In a wet agitating ball mill, a shaft 5 rotated and driven by a motor is hollow at its axial center at an upper portion, a discharge route 9 communicating with a slurry discharge port is provided, and a rotor 11 is affixed at the lower portion of the shaft. A separator 4 is composed of a pair of disks 21 and a blade 22 for coupling both disks to form an impeller, and by its rotation, a centrifugal force is applied to the slurry and media getting in the separator 4, and by the difference in specific gravity of the two, accordingly, the media having the heavier specific gravity is expelled and separated in the radial direction, while the slurry of the lighter specific gravity is discharged through the discharge route 9 of the shaft 5 in a state free from kinetic energy.