The objective of the State is to ensure the welfare of the people as stipulated in the 1945 Indonesian Constitution. One of the ways to reach this objective is by protecting the rights of land usage and ownership by the people. However, customary land (tanah hak ulayat) belonging to the Indonesian adat community is under constant threat of extinction. This is due to the increasing relinquishment of communal land by the government in the face of rising need of lands in Indonesia, especially those designated for public utility. This possesses a problem for the adat community to sustain themselves. The purpose of this study is to provide a model recommendation to prevent the extinction of customary land as well as a solution to empower the adat community. This study uses the normative legal research methodology. The legal documents and legal resources are analysed by using statutory and conceptual approaches. Both approaches are significant to examine the existing laws in addition to analyse the factual challenges revolving the preservation of customary land by the adat community. This study found that the main cause leading to the extinction of customary land is the difficulty faced by the adat community to prove the status of communal land. This is encouraged by the lack of admissibility in the evidentiary materials and a lack of written laws providing the protection of customary land. Therefore, the ideal model to prevent the extinction of customary land is through the participation of adat community to sustain assets of land and the opportunity of exchange of lands under adat law. This study contributes to the existing literature on adat law in Indonesia.