Abstract: A method and a device for confirmation automatically of the state of tightness of fastenings of railroad tracks are provided, so that from a train that is traveling over a track it is possible to detect a signal from each of the fastenings which indicates if the degree of tightness of these fastenings is sufficient, or if, to the contrary, the fastening is deficient because it is either loose or damaged. For this, a device according to the invention comprises a pressure sensor element and at least one electrically conducting element connected to the pressure sensor, whereby a variation is produced of at least one electric magnitude/value proportional to the pressure of tightness present in at least one point in said fastening during the passage of a train. The invention also relates to an insulating plate for fastenings and to railroad track plant, which incorporate a sensor device object of the invention.