A diaphragm has a configuration including a diaphragm main body, a cone part on an outer periphery of the diaphragm main body, a ring member joined to the cone part, and an edge having an inner periphery joined to an outer periphery of the ring member or an outer periphery of the cone part. This configuration improves the rigidity without changing the shape of the diaphragm main body, that is, without giving rise to a mass increase in the diaphragm main body, and keeps the sound pressure from decreasing in a high frequency range.