The authors studied the equilibrium function with 4 methods such as rail walking, twice rotating stepping tests, walking test and standing test with airplane form. These tests were performed on 4037 pupils age ranged from 6 to 17 who were free from disease, disabilities and/or other illness in Busan area. Development of eqilibrium function was observed by mean, standard deviation and their significance of each age, each sex, 4 age groups. In addition, the correlation between equilibrium function and Röhrer's index, equilibrium function and intelligence quotient were also observed. The results were summarised as follows : 1) In generals, equilibrium function grows rapidly in the age group of 9 to 11 years old. 2) There was no sexual difference, but in general, equilibrium function developed earlier in girls than in boys. 3) The direction of deviation on walking test seems more dominant to right side(37.0%) than to left side(33.5%). 4) The direction of deviation on right side(32.3%), and the direction of deviation on left twice rotating stepping test was more dominant to right to right side(39.7%) than to left side(29.4%). 5) Development of equilibrium function was poor in groups of the higher Röhrer's index(over 156) and the lower Röhrer's index(below 91). 6) In the correlation between equilibrium function and intelligence quotient, it was observed that the higher intelligence quotient, the better equilibrium function.