This study was performed to 651(330 boys, 121 girls) elementary school students in Jeju, and as the result of comparative analysis of the effect of Body Mass Index(BMI) on events of physical ability examination and children eating habits is as follows. 1. Actual condition of obesity It present that there are 494 children(75.9%) as a normal group, 91 children(14.0%) as a obesity-risk group, and 66 children(10.1%) as a obesity group. There is no significant difference in obesity level by each school year, but in obesity level by gender, girls are more than boys in normal group by 258 children(52.2%), and in a obesity-risk group and a obesity group, boys are more than girls by 55 children(60.4%) and 39 children(59.1%) respectively. 2. Relation between events of physical ability examination in each group As the result of analysis of relation between physical ability examination in each group, a normal group has good record significantly in 50m run, Sit Up, standing long jump, and 1000m long distance run-walk as compared to a obesity-risk group and a obesity group. However there is statistically no significant difference between groups in Sit and Reach. 3. Relation between weight, physical strength, and exercise habits in each group Children in a obesity group are concerned about their weight much more than a normal group, and most of children indicate the food intake control and exercise method as a right method of weight control. On the one hand, it is presented that they did not recognize their physical strength level exactly. There is no significant difference between groups in exercise habits such as exercise type, exercise frequency, and exercise time so on, and there are 145 children(22.3%) who participate in exercise program, 181 children(44.8%) who take exercise two days or less a week, and 264 children(40.6%) who take exercise for less than 30 minutes a day. 4. Relation between eating habits in each group As the result of analysis of relation between eating habits in group, there is no significant difference. Special thing is children in a obesity group had a vegetable-centered meal more than a normal group and a obesity-risk group, ate less food for a snack, and did not have an unbalanced diet very much. ※ Key words : BMI, physical fitness, eating & living habits