Recently, skill preservation of an expert has been a serious problem of the medical or production fields. This paper proposes a skill preservation system for motion acquisition of human fingers. The proposed skill preservation system is composed of a master-slave system, and the control system is based on bilateral motion control. Since a touching motion is subject to the "law of action and reaction", it is possible to decompose force information into action force and reaction force by using the bilateral control. Furthermore, human motion is acquired in decoupled modal space by using the mode quarry matrix. The decoupled modes correspond to "moving", "yawing", "grasping" tasks, and so on. Thus the skilled motion by a human is easily obtained in the modal space. The mode quarry matrix is also applied for temporal decomposition. As a result, modal and temporal analyses are realized by using the mode quarry matrices. The proposed skill preservation system is applied for grasping motion by three fingers. The experimental results show viability of the proposed method.