The invention concerns a flexible application device (1) for the high-frequency therapy of biological tissue or hollow organs, including a tubular high-frequency catheter (5) with a flexible shaft tube (6) having at least one lumen passing therethrough, a head electrode (2) arranged at the distal end of the high-frequency catheter (5), an electric line (9) with a connection (20) for a high-frequency generator (11), and a connecting element (8) arranged at the proximal end of the shaft tube (6) between the shaft tube and the line (9). An electrically conducting traction element (12) extends in the lumen between the head electrode (2) and the connecting element (8) and is fixedly connected to the head electrode (2) on the one hand and the connecting element (8) on the other hand in such a way and which is of such a tensile strength that all external forces which occur during a treatment and which act on the high-frequency catheter (5) can be transmitted to the connecting element (8) by way of the head electrode (2) and the traction element (12).
