Obesity is increasing due to the recent improvement in socio-economic level and lifestyle change. The prevalence rate of obesity among Korean is increasing and it causes various diseases and becomes a serious problem that threatens the health of the people. Hence, based on the epidemiologic investigation, the current study examines the risk factors and accompanying diseases of obesity and the effect of the exercise for the treatment and prevention. The results of the epidemiologic investigation show that (1) high blood pressure, high cholesterol, diabetes and the death rate due to coronary disease are risk factors, and (2) physical activity and exercise can reduce the risk of obesity and accompanying disease. In addition, this study suggests the groups sports activities are more effective than individual ones.