PURPOSE: To provide a speaker which has high efficiency and permits sufficiently low tone reproduction by so constituting the speaker that a dynamic type full face driving speaker and a piezoelectric speaker are combined.

CONSTITUTION: A diaphragm 7 is constituted by forming a full face electrode layer 9 through vapor deposition, etc. on one side of a high polymer piezoelectric film 8 composed of thin film of polyvinylidene fluoride or other, forming a zigzag form coil conductor layer 10 on the other side, spreading this with a frame 11 and disposing bar magnets 12 and magnetic plates 12 supporting these and simultaneously forming magnetic circuits on both sides. As a result, by connecting the low impedance terminals 17, 18 of a transformer 15 to which signal voltage input to the coil conductor layer 10 and high impedance terminals 19, 20 to the electrode layer 9 via diodes 23, 24, the speaker which permits low tone reproduction with high efficiency may be provided by making use of the advantages of the dynamic type and piezoelectric type.