A pressure-measuring sensor having an electrically-conductive separating diaphragm closing off an interior chamber of the pressure-measuring sensor to the outside, to whose exterior surface a liquid medium under pressure can be applied, and having a device for detecting a diaphragm rupture of the separating diaphragm. At least one electrode is arranged on an interior surface of the separating diaphragm which faces the interior chamber, said electrode being electrically insulated from the separating diaphragm by an insulating layer arranged between the electrodes and the separating diaphragm and mechanically connected to the separating diaphragm, a measuring circuit is connected to a capacitor formed by the separating diaphragm and the electrode, said measuring circuit measuring and monitoring a measured variable dependent upon an electrical property of the capacitor, which is changed by a medium penetrating into the area of the capacitor when a diaphragm rupture of the separating diaphragm occurs.