PURPOSE: To extract an electromagnetic transducing characteristic of the best level which the coating material has by redispersing a magnetic coating material immediately before coating.

CONSTITUTION: A magnetic coating material is injected from an injecting port 54 installed at the lower part (circular cone peak side) of a container 52 and extracted from an extracting port 55 installed at the upper part. At the time of floating, a strong shear force is given to the magnetic coating material by the movement of auxiliary media 53 such as glass by the rotation of a rotor 51, and the shear force is increased as the coating material flows to the upper part, and dispersed. The container 52 is provided with a cooling jacket 56 at the lower part side and the heat generated at the time of shearing the magnetic coating material is absorbed. The magnetic coating material after redispersion in a redisoersing device 5 is guided from an extracting side of the redispersing device 5 into a duct 6, supplied through a filter 7 on its way to a coater 8 and coated on a supporting body 9.