Abstarct: This thesis presents the control of rigid satellite attitude with regard to the uncertainty of inertia and external disturbances and also measuring only outputs of the system. Angular velocity is assumed to be unavailable, so a finite time extended observer is designed to estimate angular velocity and total disturbances. Then, a control signal is generated baxsed on the estimated angular velocity and attitude of rigid body satellite. The proof of stability of control system using the Lyapunov theory. Finally, a numerical simulation is presented to demonstrate the effectivness of the proposed control method.