Magnetic circuit for speaker, and speaker using same

This magnetic circuit has a magnet, a top plate, a bottom plate, and a yoke. The magnet has a first surface and a second surface. The second surface is positioned in a first direction with respect to the first surface and disposed in such a manner as to be parallel to the first surface. The first and second surfaces are both magnetized. The top plate is disposed on the first surface of the magnet, while the bottom plate is magnetically coupled to the second surface of the magnet. The yoke is magnetically coupled to the bottom plate and is provided in such a manner as to extend in the first direction from the bottom plate. The yoke has a pole face that faces the top plate. A portion of the yoke that forms a pole face is provided with a magnetic saturation part for inducing magnetic saturation. The magnetic saturation part has a shape in which the area size of the cross-section thereof taken in a direction perpendicular to the first direction decreases toward the tip of the yoke in the first direction. 磁路具有磁体、顶