Purpose: This study investigated the sexual behaviors, emotional state, and suicide-related characteristics of female adolescents with sexual experience. Methods: This is a secondary data analysis study using the data of the 11th (2015) Youth Health Behavior Online Survey. The subjects were 889 female students who had sexual intercourse experience in middle and high schools in the Republic of Korea. For data analysis, descriptive statistics, x2 test, and hierarchical logistic regression were used. Results: Among the subjects, 22.2% reported having experienced homosexual or bisexual relations. The sexual debut time of 31.9% of the subjects was in elementary school or earlier, while 8.1% and 10.7% experienced pregnancy and sexually transmitted diseases, respectively. They reported negative emotional states (high stress 51.7%, unhappiness 17.8%, depressive mood 9.8%) and substantial suicide experiences (suicidal ideation 33.6%, suicidal plan 16.6%, suicidal attempt 13.2%). Through hierarchical logistic regression (Cox & Snell R2=.31), the influencing factors for suicide ideation identified included being subjected to sexual relations, experience of pregnancy, perceived stress and happiness, and depressive mood. Conclusion: It is important to prevent negative mental health consequences among female students with early sexual experience. Sexual education should strengthen their physical and mental safety through psychological care strategies.