Objectives: In recent years, pregnancy rate among female adolescents has increased and caused a variety of physical and social problems. Therefore, this study aimed to investigate sexual behavior, delinquent behavior, and pregnancy rate among Korean female adolescents. Methods: In light of the growing interest in adolescent pregnancy, this study conducted a web-based survey, titled "The 2006 Youth Health Risk Behavior Survey." The Korean Center for Disease Control (KCDC) collected questionnaire responses from 34,200 young women. The collected data were analyzed through chi-square test and logistic regression using SPSS Win 14.0 version. Results: This study analyzed main factors, which can predict pregnant experience. The statistic results showed two types of the predicting factors: (1) personal factors: sexual relations after drinking (odds 25.1), Narcotic drug taking (odds 13.0), sexual violence act (odds 7.0), part-time job(odds 2.5), drinking, smoking ; and (2) environmental factors: stepfather(odds 4.2) and natural mother. Conclusion: The influential factor identification for predicting pregnancy rate is important to develop an effective education program for preventing the adolescent pregnancy. The education programs with referring to the identified factors can contribute to reducing the unwilling pregnancy rate of young woman.