PURPOSE: To suppress absorption of oil from alloy containing oil by covering one surface and an axial periphery of a core wound through an insulator with shielding plates, and forming a bearing press-fitting hole inside the axial periphery of the plate of molding resin for fixing the core to the plate.

CONSTITUTION: A shielding plate 1 for shielding leakage magnetic flux over one surface and an axial periphery of a core 2 wound with a driving winding 4 through an insulator 3 and resin 5 for forming a bearing press-fitting hole 6 are integrally molded. In this case, a contracted part (not shown) provided at the plate 1 is so sealed in the resin 5 as to surround the hole 6, thereby forming a thin cylindrical resin part 5a. Thus, a variation in a hole diameter due to molding shrinkage of the resin is reduced, and absorption of oil to the resin at the time of sealing a bearing containing oil is suppressed.