It is very important to measure the yarn tension in the textile process for improving the productivity. The contact type tension detection systems have been widely used in the textile industry until now. However, these kinds of conventional contact type tension detectors have a friction problem between detector and yarn. the objective of this study is to develop a noncontact type tension detecting system in spinning process. In this paper a system to convert the frequency of yarn to the tension was devised by inducing an equation between frequency and yarn tension from the wave equation. The frequency of yarn was measured with the optical fiber sensor, and from this frequency the yarn tension was obtained using the induced equation. The validity of the non-contact type tension detection system was verified by the experiments.