Purpose: This study was done to investigate cybersex addiction, gender egalitarianism, sexual attitude and the allowance of sexual violence in adolescents, and to identify the relationships among these variables. Method: The participants were 690 students from two middle schools and three high schools in Seoul. Data was collected through self-report questionnaires which included a cybersex addiction index, a Korean gender egalitarianism scale for adolescents, a sexual attitude scale and a scale for the allowance of sexual violence. The data was analyzed using the SPSS program. Results: Of the adolescents, 93.3% reported not being addicted to cybersex, 5.7% reported being mildly addicted, 0.4% moderately addicted, and 0.6% severely addicted. Cybersex addiction, gender egalitarianism, sexual attitude and the allowance of sexual violence in adolescents were different according to general characteristics. Cybersex addiction of adolescents correlated with gender egalitarianism, sexual attitude and the allowance of sexual violence. Conclusion: Gender egalitarianism, sexual attitude and the allowance of sexual violence in adolescents were influenced by cybersex addiction. Therefore, nursing interventions for prevention and management of cybersex addiction need to be developed and provided to adolescents. In addition, varied programs for teaching sexuality to adolescents should be developed and provided.