Land is an element that can not be separated in human life in every form of the activity either directly or indirectly and land is also something important for humans. The goverment of the Republic of Indonesia has a mature planning in the field of agrarian, with the existence of a clear regulation, and contained in the basic law of agrarian number 5 of 1960. All of the citizen of Indonesia have land rights, one of them is customary land and can be diverted. land in Indonesia must be registered to obtain legal certainty with the issuance of certificate of property rights on land. With the existence of a large land, land disputes will certainly occur, one of them is double certificate. This research aim to : 1). for knowing the transition proses customary land based on customary law. 2). for knowing judge legal considerations on making a decision based on court decision number 35/Pdt/2020/PT.JAP. This research uses normative legal methods by studying various law and regulations regarding customary land, customary law and basic law of agrarian. The transition proses of customary land is done by submitting some fee in front of the customary leader, custom society and Lands Titles Registar as a witness. And then, when the judge deciding for double certificate of ownership of land rights, based on article 32 paragraph 1 goverment regulation on land registrasion jo Indonesia supreme court decision number 5/Yur/Pdt/2018 , when both of which have autenthic evidence, the strongest evidence is the old certificate.