<p>Tension estimation is important in the maintenance of cable structures. Nielsen–Lohse bridges are tied arch bridges with inclined cables intersecting each other and connected by clamps at intersection points. Currently, the higher order vibration method is used to estimate the cable tension of Nielsen–Lohse bridges. Because the higher order vibration method is a tension estimation method for a single cable, it is necessary to remove all intersection clamps to apply this method to a Nielsen–Lohse bridge. However, removing and reinstalling the intersection clamps requires an aerial work vehicle, which is time-consuming and labor-intensive. Therefore, previous studies have proposed estimating the tension of two cables connected by a single intersection clamp using natural frequencies. This previously proposed method can estimate the tension of two crossed cables simultaneously without removing the intersection clamp. However, because most cables are often connected to multiple cables by multiple intersection clamps in Nielsen–Lohse bridges, the application of the previously proposed method is limited. With this background, this study developed a method for estimating cable tension using the mode shape of the cable, without removing any intersection clamps. The proposed method enables the simultaneous estimation of bending stiffness and cable tension. Moreover, this method was validated through numerical simulations and experiments. In the numerical experiments, the maximum estimation error for both tension and bending stiffness was within 1% when measurement error was not included. In the experiment, the tension was estimated with a maximum estimation error of 6.6%. By taking the average of the three estimation results, the estimation error of the tension was 2.7%, and that of the bending stiffness was 8.8%. Thus, the proposed method was validated.</p>