This paper represents torsional vibration control of a flexible manipulator. For torsional vibration suppression, the feedback control is designed based on Lyapunov's direct method. The feedback control of torsional motion of the flexible manipulator is derived by considering the time rate change of total energy of the system. If the both angle velocity and the angle of the manipulator are known, all the modes of the actuators can be controlled simultaneously. This approach has the advantage over the conventional methods in the respect that it allows one to deal directly with the system's partial differential equations without resorting to approximations. The numerical simulations are performed by using FILT (Fast Inversion of Laplace Transform) method of numerical algorithm and the effectiveness of the feedback controller is verified.