Abstract: The present invention relates to a piezo-electric stretching detector which is used for measuring the positive and negative stretching on the surfaces of rigid structures using electric signals, wherein said detector can be attached by a force connection onto said surfaces in a compressible or non-removable relation. This stretching detector has a high sensitivity in all stretching directions and is made of a piezo-ceramic material which is applied in a thin layer on at least one surface of a flexible metal sheet or which is fixedly attached to said metal sheet in the shape of a moulded body. At least one of said stretching detectors can be arranged on the free abutting end of at least one resilient pressure body which is imbedded in the reception housing of a stretching sensor. The stretching sensor further comprises members for pressing the reception housing onto the surface to be measured.