Fill level measuring device for determining and/or monitoring a fill level, having - a membrane which is able to be vibrated, said membrane being surrounded by a rigidly formed membrane edge and having a vibration body in the front side direction, - a drive device arranged in the rear side direction of the membrane in the form of a drive stack having piezoelectric elements to enable vibration of the membrane and/or to convert a vibration of the membrane into an electrical signal, - a fastening device arranged in the rear side direction of the membrane for fastening the drive device to the membrane edge, - wherein the drive device has a drive front side facing the membrane, characterised in that - the fastening device (13, 13*) is formed to be disc-shaped or web-shaped and is firmly connected to the membrane edge, - at least one pressure transmission element is arranged between the membrane and the drive front side of the drive device in such a way that the membrane and the drive front side are coupled with each other for vibration transmission; - wherein the pressure transmission element engages with the membrane as centrally as possible in the front side direction and, at the rear side, has at least two legs which protrude through the disc-shaped fastening device or surround the web-shaped fastening device, but do not touch the fastening device, said legs being tensioned against the drive front side of the drive device and being formed to be long enough that the fastening device does not come into contact with the drive device and means (16, 17) are present to adjust the preload force of the drive device with respect to the pressure transmission element and above this against the membrane. - a membrane which is able to be vibrated, said membrane being surrounded by a rigidly formed membrane edge and having a vibration body in the front side direction, - a drive device arranged in the rear side direction of the membrane in the form of a drive stack having piezoelectric elements to enable vibration of the membrane and/or to convert a vibration of the membrane into an electrical signal, - a fastening device arranged in the rear side direction of the membrane for fastening the drive device to the membrane edge, - wherein the drive device has a drive front side facing the membrane, characterised in that - the fastening device (13, 13*) is formed to be disc-shaped or web-shaped and is firmly connected to the membrane edge, - at least one pressure transmission element is arranged between the membrane and the drive front side of the drive device in such a way that the membrane and the drive front side are coupled with each other for vibration transmission; - wherein the pressure transmission element engages with the membrane as centrally as possible in the front side direction and, at the rear side, has at least two legs which protrude through the disc-shaped fastening device or surround the web-shaped fastening device, but do not touch the fastening device, said legs being tensioned against the drive front side of the drive device and being formed to be long enough that the fastening device does not come into contact with the drive device and means (16, 17) are present to adjust the preload force of the drive device with respect to the pressure transmission element and above this against the membrane.