A simple and efficient adaptive control scheme is developed to automatically tune PD control gains for two-link flexible manipulator. The manipulator is modeled using Lagrange and assume mode method. The adaptive algorithm is developed for hybrid PD-PID controller in which the PD controller is for rigid body motion control and the PID is for end-point vibration suppression. The simple adaptive control scheme continuously tunes only the proportional and derivative gains of the PD controller depending on the error value without switching. The proposed control law is tested in Matlab/simulink simulation environment. The effect of white noise and rectangular wave disturbance on the proposed controller is extensively studied. Also, effect of changing input signal is also investigated. Performance of the proposed controller is compared with hybrid PD-PID controller in terms of input tracking and vibration suppression. The results show the effectiveness of the proposed direct adaptive hybrid PD-PID controller.