The purpose of this study was to emphasize the importance of exercising programs for the children with mental retardation and present basic materials to develop effective exercising programs to improve their physical fitness (strength muscular endurance, power, flexibility, balance and cardiorespiratory endurance), body composition(%fat, soft lean mass, waist-hip ratio and BM) and bone mineral density(BQI/ SOS, BUA, T-score) by applying rope jumping for the children with mental retardation To achieve the purpose of these study, it was conducted on 22 subjects(experiment group of 11 subjects and control group of 11), 60 minutes per session, three times a week, for 12 weeks. The results derived from the tests were as follows. 1. The changes in physical fitness of the experiment group and the control group before and after rope jumping showed improvement in average physical fitness in grasping power, sit-ups, hopping and bending forward but did not show any statistically significant difference. However, standing on one foot with eyes closed showed increase in average with pre-test average of 2.63 and post-test average of 10.48, and also showed statistically significant difference(t―3.979, p<.01). Heart beats also showed statistically significant decrease since exercise was given with pre-test average of 9818 and post-test average of 81.81. On the other hand there was no significant difference in all factors of physical fitness measurement in control group before and after rope jumping exercising program 2. Since rope jumping was conducted, the average of waist-hip ratio of the experiment group was reduced from .87 before exercise to .82 in after exercise, which means statistically significant difference(t=1.97B, p<.05) in body composition Except 仕lis, %fat, BM1 and soft lean mass was improved after exercise but it was not statistically significant difference. In the control group, there was no statistically significant difference in % fat, waist-hip ratio, BM and soft lean mass. 3. The changes in bone mineral density before and after exercise was showed statistically significant difference in BUA(t=-2.877/ p<.01) and T-Score(t=-2.877/ p<.01) of the experiment group. But, the BQI and SOB in the experiment group and all the aspects of bone mineral density in the control group did not show statistical significant difference.