Although previous studies have paid much attention to the condylar movement in adults with permanent dentition, little attention has been paid to such movement in children. In this study, we therefore clarified the difference in habitual open and close movements at the condyle in children. Three groups of subjects were used; primary (10 children), early mixed (10 children), and permanent dentition (10 adults). The habitual open and close mandibular movement of each subject was measured using a TRIMET, which can three-dimensionally analyse the simultaneous movements of multiple points on the mandible of a subject. The measurements were then compared among the three groups. The three-dimensional analysis detected significant difference in all directions between children with primary dentition and adults with permanent dentition: primary dentition had the smallest anterior-posterior and superior-inferior directions, and the largest left-right direction. Coincidence of the open and close tracks occurred in the adults (adult group) but not in the children (primary and early-mixed dentition groups). The early-mixed dentition group showed tracks that were between those for the primary dentition group and the adult group. These results suggest that the regularity of the condylar track might be well established with dental development.