A self resonance-type sound-producing speaker that is waterproof and readily attachable. The self resonance-type sound-producing speaker includes an actuator speaker unit and a polymer foam arranged to cover the entire outer surface of this speaker unit and converts the vibrations from the speaker unit into plane waves to externally produce sound. The polymer foam preferably has the expansion ratio of 10 to 30 times and the closed pore structure. The thickness of the polymer foam is preferably not less than 2 mm and is more preferably not less than 3 mm.