Objective We aimed to investigate the influence of area-level factors on adolescent suicide and to determine which variables differ according to age and sex. Methods We selected variables that were available for collection through an online database from 2005 to 2015 in the Korean Statistical Information Service and the Korea Labor Institute. We used administrative districts of Korea in 2017 for geographical classification. We examined the relationships between regional suicide rates and area-level variables in male and female subjects aged 10-14 years and 15-19 years. In addition, we analyzed area-level variables in adolescents aged 15-19 years according to sex. Results Our findings indicated that several area-level variables affected adolescent suicide rates, varying according to age and sex. Economic problems were shown to be more associated with suicide in male adolescents than in female adolescents. On the other hand, social fragmentation and health services were shown to be more associated with suicide in females. Conclusion Suicide in adolescents was attributable to area-level factors such as economic status, social fragmentation, and community health services. By identifying area-level variables affecting adolescent suicide rates, we will be able to contribute to implement mental health policies related to adolescent suicide.