In this paper, we discuss a simple distributed parameter controller for large space structures with lumped and distributed flexibility. As a simple example of large space structures, we consider two flexible beams connected by a spring. Dynamic equations of the distributed parameter system are derived by means of the Hamilton's principle. We introduce the Lyapunov function related to the total energy of the distributed parameter system and derive a simple sensor output feedback control law. Using the characteristic of the differential operator and the invariance principle, we prove the asymptotic stability of the closed-loop system and the convergence property to the desired stationary state. In order to demonstrate the validity of the derived model and the proposed controller, experiments have been carried out.