To provide a loudspeaker for various acoustic devices that has superior low sound frequency reproduction capability, without causing magnetic distortions.

This loudspeaker has a turnable conductor disk 10, a magnetic circuit with a magnetic gap 18 generating a magnetic field in the vertical direction with respect to a disk with the conductor disk 10 in-between, electrodes 19a, 19b placed to a center and an outer circumference of the conductor disk 10, and a shaft 12 whose one end is turnably fitted to part of the conductor disk 10 in the radial direction and whose other end is turnably fitted to a diaphragm. Since the conductor disk 10 makes reciprocate circular motion in a uniform magnetic field and the shaft 12 connected to the conductor disk 10 which drives the diaphragm 13 with a vertical linear motion converted from the circular motion produces sound, superior acoustic characteristic which has no magnetic distortion is obtained.