This Journal written to discuss the inheritance of adopted children is being by custom, in this case is the Sasak indigenous, in District Sembalun East Lombok regency, West Nusa Tenggara province. The purpose of this study, to understand, analyze and find the factors behind Sasak indigenous do adoptions and the child adopted inherit rights in perspective of Sasaknese customary law particularly in Sub Sembalun East Lombok West Nusa Tenggara province. The method used in this thesis is empirical legal research. The approach used is approach Sociology of law. The results showed that the adoption of children in Sasak indigenous being to children who come from families or relatives and are not members of the family. This is due to reasons other than the removal of a child to get a descent is also guided by a sense of humanity and child's welfare. The process of adoption was done by Sasak indigenous people with ceremonies that name was ‘begawe' or ‘roah' ceremony. Kinship of the adopted child to his biological parents is not interrupted even though he entered to adopted parents. The Position of adopted child in a family of adoptive parents is a biological child, thereby functioning as a continuer descent and serves as the heir and aligned his position with biological children. Thus the provisions adopted children inherit the heirloom adoptive parents including inheritance. Instead, the adopted child is not entitled to inherit from parents who are treasure doe tengaq is inheritance from parents who was not divided heir to the brother. And adopted children entitled to inherit the legacy of his biological parents.