Objectives: Pre-marital sex is increasing all the year in the city of Jayapura, which is inhabited by several tribes among the other tribes such us Tobati and Enggros. The influence of location on the development of Tobati and Engros tribal triggered changed in terms of change in socialization of teenagers. Purpose: The aim of this research was to establish the concept of prevention behavior sex marriage of pre-teen of Tobatiand Enggrostribes in the town of Jayapura in terms of concepts of thought and feeling, personal, concept of the source establishments and information against the concept of culture in both tribes. Method: this research was used etnometodologi approach. The informant assignment done on a purposive, consisting of parents, teenagers and the leader of the tribe. The data obtained through the observation, interview and focus group discussion. Data analysis is used cultural theme. Result: Thoughts and feelings are not yet adequate precautionary behaviour regarding pre-marital sex – marriage. Knowledge should be adequate in terms of pre-marital sex – marriage, forms of pre-marital sex – marriage prevention impact resulting from pre-marital. Personal reference factors about pre-marital sex – marriage is from parents especially Moms and this became the reference. Discussion: Family teaching and planning is more important to teach teenager inside the family, moreover the government should protect and use the positive culture to prevent their family from free life style at this moment.
