A loudspeaker includes the following components: a frame (5) that has a magnetic circuit (4) including a magnetic gap (4a) therein; and a diaphragm (6) that is bonded to a voice coil (7) fitted into the magnetic gap (4a) in the center thereof, and to the periphery of the frame (5) along the outer periphery thereof. The magnetic circuit (4) includes a yoke (1), a magnet (2), and a top plate (3). Tongue-shaped flanges (1a) are disposed at a substantially equidistant spacing in three positions to protrude from the top end face of the yoke (1). The total area of these tongue-shaped flanges (1a) in the three positions does not exceed a half of the total area corresponding to the flange part without flanges (1a). The frame (5) also includes engaging parts (5a) each for receiving one of the tongue-shaped flanges (1a) therein.