This paper proposes an estimation method of functional mode in grasping/manipulation motion in scaled bilateral control system. In the conventional method, however, it is presupposed that functional-mode is predefined. By using proposed method using principal component analysis(PCA), time-variable functional mode of control system and human motion is directly estimated from motion information without considering predefined functional mode. In grasping/manipulation motion in scaled bilateral control, it is possible to estimate the principal functional mode and evaluate the performance of control systems. Validity of the proposal is confirmed by experiments.