A thin timepiece comprising a flattened casing, a display unit, a diaphragm having its peripheral portion carried by the casing to generate sound, a piezoelectric element mounted on the diaphragm and a module for driving the display unit and the piezoelectric element. The diaphragm and the piezoelectric element are formed ring-like so that the space in the central hole of the ring-like diaphragm and piezoelectric element is used for a part of the occupation space of the electric cell in the casing and that renewal of an electric cell is facilitated by the provision of the space for the cell in the diaphragm and the piezoelectric element.