The life cycle that must be passed by humans is adolescence. In adolescence these sexual impulses increase, so intercourse with the opposite sex will continue on the relationship of sexual activity. Unwanted pregnancy in adolescence is one of the effects of free sex behavior. The purpose of this research is to analyze the influence factors for the risk of unwanted adolescence pregnancy in Kutai Kartanegara Regency. The research uses the analytic observational with Cross Sectional Study design. The population in this research are high school girls of class X and class XI in Kutai Kartanegara Regency. While the sampling using Proportional stratified random sampling technique that has been determined based on inclusion criteria with a sample size of 390 people. The result of correlation test shows that there is significant influence between social institution, peer/ community, adolescent information and media knowledge about reproductive health, to the risk of unwanted adolescence pregnancy with the value of p: <0,05 . The result of logistic regression test shows that there is significant influence between social institution, peer/community, information media and media knowledge about reproductive health against risk of unwanted pregnancy is shown with p value <0,05. Keywords: Social institutions, peer, community, information media, knowledge, unwanted pregnancy, adolescence.