PURPOSE: To radially anisotropically form in an axial magnetic field by forming first, third cores of a ferromagnetic material, forming second, fourth cores of a nonmagnetic material, and setting the first core larger in size near its cavity than the third core.

CONSTITUTION: In the flow of a magnetic flux passing an arcuate cavity 14, stationary and movable first, third cores 44a, 46a arranged around a cavity 14 are formed of a ferromagnetic material, and second, fourth cores 44b, 46b are formed of a nonmagnetic material. The size of the vicinity of the cavity 14 of the core 44a disposed at the side in which the cavity 14 protrudes is specified larger than the core 46a of the other side so that the cavity 14 is radially passed. As a result, magnetic powder in the melted resin is uniformly radially anisotropically set. Thus, a magnet is radially anisotropically set by the formation of the axial magnetic field irrespective of its thickness.