PURPOSE: There were rapid socio-environmental changes in Korea caused by industrializations in last thirty years. Those changes are : first, abrupt changes from the environments with closed Confucian ideas to the liberal democratic society, second, agricultural society changed to industrialized society and families with two or three generations are broken down into nuclear families at each generation, third, the annual personal income was increased from less than 100 US dollars in 1960' s to 10,000 US dollars in recent years, and some peoples show luxurious consuming, adolescents became feeble minded and peoples avoid jobs with dirty or hard works, fourth, one third of young couples employed are dual income families and they left their child to a neighbourhood, or a day-care center or infant home for caring children during work hours, fifth, the school education focused on the entrance examination of the university that causes conflicts between parents and offsprings. METHODS: The author studied differences of family environments between student group (SG) consists of middle and high school students, and juvenile delinquent group (JDG) confined in prison. It is revealed that the extent of misconduct depend on different factors such as the age of study subjects, absence of parent (s) in the family, total family income, parents' educational level, personal expenses and the conflicts between parents. The conditions for those factors were worse in JDG as compared with that of SG. The differences were statistically significant. As long as the extent of delinquency is concerned, delinquent points of JDG were significantly higher as compared with that of SG for all factors. RESULTS: In order to prevent juvenile delinquency in Korea, it is recommended that educational level and the living standard of the lower class peoples should be raised, the sound families which do have less conflicts should be established as many as possible, defective families should be reduced by decreasing divorce rate and car accident, the current educational system that is making much more conflicts between parents and their offsprings should be changed so that their given temperament would be brought up to the highest level, parents who do not want to see misbehavior of their children should not do actions that are considered not to be done by youngsters and must set a good example, parents should act up to what they say, adult education is to be developed so that to rear their children emotionally sound as much as possible. CONCLUSION: It is recommended that : 1) We, pediatricians must concern not only for their physical and mental health of the children, but also intervening their families. 2) When we, pediatrician would find any unhappy children leaving parents, should lead and help them to receive proper love and home-education. 3) Day-care nurseries, nursing schools and kindergartens that are under control of a local district office must employ qualified teachers and enough spaces. 4) Home-education should be done by the parents in each family. In order to give better home-education we have to teach on rearing babies and children and on home-education during the middle, high school ages in female. 5) The society has the responsibility of admitting and educating all unhappy children in institutional facilities. 6) As long as the economic conditions permit, compulsory education for one or two years of 5 to 6 years-old children should be performed to learn about social moralities and basic regulations.