The authors propose a hand posture estimation system in real time and with high accuracy, for robot hand control and human interface with hand motions without no sensors attached to the users. This method searches the similar image quickly from a large volume of previously-sorted image database which contains complicated shapes and self-occlusions of the human hand. Because the system doesn't need any special peripheral equipment such as range sensor and PC cluster, and works with a note PC using a single high-speed camera, the user can control and make a dexterous robot hand behave as he/she does, and use the system as an information input device by moving his/her hand and fingers.