For robot hand design to reproduce the work space of the fingertip of a person, we proposed a method to measure the movement of the fingertip using optical motion capture and estimate the joint that reproduces it. For this time, trial the robot hand based on this, and make sure that the design is possible. we examine the characteristics of the joint structure of the model from the motion of the fingertip of the estimated model. As a result, compared to other robot hands, a robot hand with a large overlap of finger work spaces was designed. This is because the joints of the fingers are in a twisted relation to each other, the workspace of the fingertip has become a distribution towards the inside.