In spite of the development of scientific and medical technology, the rate of prevalence and death of the chronic disease gets higher. Therefore people come to know prevention is more important than treatment in disease. In Western, it is nearly after 1970`s when it is revealed that the major factor of chronic disease comes from habitual behaviors in everyday life. But that is common idea in Oriental Medicine since thousand years. In Oriental Medicine, the main cause of disease is composed of natural factor including climate condition, living-life factor, psycho-social factor, constitutional factor, inbody-pathologic-substance factor, and other factors including habits of using drug and medical service, injury, environmental pollutions, and occupational etiologic factors. Among these, the major factors of disease in modern society are lifestyle factors like the tendency of choosing and intaking food, the level of physical activity and labor, smoking and drinking alcohol, psychological tendency, the habits of using drug and medical service and so on. This is a practical aspect of oriental medicine where the most important etiologic factor comes from human behaviors, not from external factors like germ or virus. So that etiology in Oriental Medicine where improvement in the way of life is needed to prevent disease would play an important role in modern society.