A magnetic circuit includes a cylindrical yoke member having an inner circumferential surface and a collar formed at one end thereof and turned back substantially at right angles, and a plurality of permanent magnet segments of a partially circular arc in cross section having respective outer surfaces attracted magnetically to the inner circumferential surface of the cylindrical yoke member and respective one end faces attracted magnetically to the collar of the cylindrical yoke member. The magnetic circuit is manufactured by a method including the steps of magnetically attracting the permanent magnet segments to an outer peripheral surface of a center rod, causing the magnet segments in a magnetically attracted state to face the yoke member, using a nonmagnetic supporter to regulate the magnet segments in position, extracting the center rod from the magnet segments in a position-regulated state, and magnetically attracting and fixing the magnet segments to the yoke member. The magnetic circuit is applied to an actuator or a speaker.