PURPOSE: To enable the reproducing of individual motions of a jaw of a patient by linking a relative motion relationship between upper and lower jaws to a sensor-computer robot in stead of jaw joint analysis unavoidably with substantial difficulty and uncertainty in the acquiring of data so far when a denture is prepared.

CONSTITUTION: A sensor 16 is mounted on a jaw or a tooth and the direction of motion, amount and the like of the jaw are measured and caught ignoring the existence of a jaw joint. The data caught are sent to a computer 3 to analyze and record and a multi-axis robot 1 having a lower jaw base 15 mounted thereon is operated based on the data. This enables the reproduction of a natural occlusal motion of an individual patient to allow actions such as longitudinal, horizontal, vertical and spiral motions and tilting corresponding to the upper jaw base 5 fixed.