PURPOSE: To reduce a leakage magnetic flux from a bottom plate and to elevate a magnetism utilization factor by jointing a frame made of a high magnetic permeability material, to the outer peripheral surface of a top plate, and arranging a resin magnet which cancels the leakage magnetic flux, between the plate and the frame.

CONSTITUTION: A cylindrical flange 8, which is perpendicular to a bottom plane, is formed at the center hole of the bottom plane of the frame 4 which is made of the high magnetic permeability, and the inside diameter of the flange 8 is made to be equal to the size of the outside diameter of the top plate 2, then, the frame 4 and the plate 2 are jointed together by swaging. Then, the plate 2 of a magnetic circuit for a speaker and the frame 4 are stuck on the upper surface of a ring shaped ferrite magnetic 3 combined on the bottom plate 1. Next, the resin magnet 5 for canceling, which is made by mixing and kneading a samarium-cobalt series together with the resin and is magnetized, is stuck between the part of the side surface 7 and the flange 8 of the frame 1 by the frame 4, and the leakage magnetic flux from the plate 1 is reduced.