Control Moment Gyros (CMG) has been expected to be applied to an earth observing satellite in recent years. However it is not easy to control it because CMG has a singularity condition and a major source of disturbance. Although there are many singularity avoidance logics, these use much resource of computer mounted on satellite. From the previous background, this paper presents a new but simple CMG steering law using preferred initial gimbal angles and null motion for high accurate attitude control system on an agile satellite. Preferred initial gimbal angles are decided by evaluating function considering inner state of CMG.