To provide a loud speaker wherein deterioration in a shape and the rigidity at an outer circumferential part of a diaphragm obtained by injection molding a thermoplastic synthetic resin is eliminated.

By using the diaphragm 8 by thickening a thickness t2 of the outer circumferential part 15 more than a thickness t1 at an inner circumferential part in the vicinity of a rising part 14 so as to uniformize the surface density between the inner and outer circumferences, the loud speaker wherein no dip takes place in a middle frequency band can be obtained.