A thin speaker structure comprises: a long support frame; a magnetic circuit member; a voice coil; a membrane; wherein the magnetic circuit member and voice coil are rounded and the membrane includes an elliptic surrounding and an elliptic body with a center portion and a peripheral portion; the peripheral portion is fixed to a bottom edge of an inner surface of the surrounding and the center portion corresponding to the peripheral portion defines a rigid strengthened region in a longer elliptic shape; the center portion has a length of a long side longer than a diameter of the voice coil at a predetermined distance; whereby the elliptic body is combined with the circular voice coil to form a vibrating structure in order to increase the rigidity of the membrane.