PURPOSE: To secure fixing strength of FG magnets so as to prevent magnetic noises by providing a bar link section, the central part of which is erected in the axial direction, a plurality of through holes which respectively pass through the lower surface section, flange section and lower surface section, and upper surface section of a rotor yoke to the rotor yoke, and then, fixing the FG magnets to the through holes.

CONSTITUTION: One end section of the rotating shaft 2 of a rotor l is put in and fixed to a bar link section of a rotor yoke 2. An annular driving magnet 6 counterposed to the coil 23 of a stator coil 20 is fixed concentrically to the yoke 3 and, at the same time, a flange section 5 is annularly erected from the outer peripheral edge of the yoke 3 and FG magnets 10 are formed on the outer periphery of the flange section 5. In addition, a plurality of through holes 9 which pass through the lower and upper surface sections the yoke 3 near 12 the flange section 5 and the resin members constituting the FG magnets 10 are hardened through the holes 9 as if the resin members are passed through the yoke 3. Therefore, the FG magnets 6 can be easily fixed and the magnetic noise can be prevented, because the leakage of magnetic fluxes is reduced.