This paper proposes a robust motion-copying system using the motion-data memory. A motion-copying system has been proposed as the system of saving and reproducing the human motion. In the conventional method, the reproduced motion is different from the saved motion when an unexpected force inputs the system. Therefore, the conventional system may cause the destruction of the environment. To solve this problem, the robust motion-copying system is proposed. The proposed motion-copying system uses the saved force and position information in the master side and the force information in the slave side, although the conventional motion-copying system uses just the saved force and position information in the master side. Therefore, the proposed system divides the estimated force into the reaction force from the environment and an unexpected force by using the motiondata memory. Since these forces are compensated separately, the unexpected force does not affect the reproduced motion. As a result, the robust motion-copying system is realized. The validity of the proposed method is verified by the experiments.