PURPOSE: To reduce an eddy current and to thin an apparatus by laminating a stator corresponding to a rotor, in which magnets with magnetic poles alternately differing in the circumferential direction are arranged in a plane, through winding a magnetic plate material in the direction along the plane of said rotor.

CONSTITUTION: A rotating shaft 11 is rotatably borne by two housings 12 and a disc rotor 1 is fastened to said rotating shaft. Said rotor 1 is formed by a magnet with polarities alternately differing in the circumferential direction. Said housing 12 is die-cast by aluminum, etc., and annular recesses 12a for stator 13 are simultaneously molded in parts of said housing, to which the rotor 1 corresponds. In said stator 13, a magnetic plate member 14 is spirally wound on the recess 12a to laminate the stator, and a plurality (six in the drawing) of cores 13a are provided at equal spaces in the circumferential direction and coils 3 are wound round said cores.