PURPOSE: To reduce a crosstalk among a plurality of channels by constituting magnetic materials by sintered ferrite of high permeability and constituting a nonmagnetic material for shielding interposed among the magnetic materials by nonmagnetic sintered ferrite.

CONSTITUTION: A fitting hole 6 for a shaft is formed to a rotor 1 and a fitting hole 7 for a supporter to a stator 2. The rotor 1 contains a disk 3 consisting of a sintered body of ferrite powder, which is nonmagnetic at least working temperature (the normal temperature or more), one part of the disk has an annular projecting section 8, and the projecting section fills the role of the shielding of nonmagnetism. Two annular high-permeability ferrite sintered bodies 41, 42 are united and attached to the surface of a substrate 3, and windings 91, 92 are coupled with the surfaces of these ferrite sintered bodies. The stator 2 is also constituted similarly by a nonmagnetic disk 11 with an annular projecting section 10, annular magnetic ferrite sintered bodies 121, 122 on the surface of the disk, and windings 131, 132 coupled with the surfaces of the sintered bodies.