Runners can practice by themselves when and where they can. If a training partner who is similar in pace runs on their side, runners are able to acquire more competitive motive than alone. Also comparison with another person is essentially expected to reflect their own running form. We design and develop a wearable system of running support, which offers a virtual competitor based on their body motion. They can practice with motive keeping the pace and consciousness of stabilizing body motion. For generating the virtual competitor, the system has two significant functions, which are detecting changes of their body motion related to the pace and the representation of hypothetical position relationship between them and the virtual competitor, in addition to monitoring technologies with sensors. © 2011 Springer-Verlag.