Abstract: A device for the internal inspection of pipelines under operation, such device sensing and registering the unevenness of the internal pipeline surface on the principal of mechanical-electrical sensing of the internal pipeline cross section. The device is composed of a supporting body to which at least one packing cuff and symmetrically placed displacement sensing elements are attached, the sensing elements having rotatable shafts to which pivoted sensing arms are connected. The arms are in engagement with a weakened cylindrical part of a packing cuff which is disposed about its entire perimeter in contact with the internal pipeline wall. Potentiometric, piezo-electric or other sensing elements are used for transformation of departures of the size of the passage through the pipeline to electrical signals.