Two wheel mobile manipulator has the potential of becoming a multi-skilled robot in the field of robotics and it is already implemented by using inverted pendulum control. Centre of gravity position (COG) is controlled to achieve the balancing of robot. Since vibration of manipulator arms affect to the COG positions of the inverted pendulum, balancing of the robot deteriorates. Therefore, vibration control of manipulator arms of the mobile manipulator is proposed in this paper. Feedback signal for vibration suppression is introduced to null space of manipulator. Simulation and experiment was carried out to check the validity of the proposed method and the results prove the effectiveness of the proposed method.