3D cadaster is a tool in a land administration system to digitally manage and represent stratifiedrnrights, restrictions, and responsibilities (legal models) and their corresponding physical modelsrnsuch as buildings, utilities, on, above or under the ground surface in 3D. In Adama Town thernregistration of land holders in the time being cannot expresses the 3D information and the 3Drncadastral data modeling application. Using 2D cadaster data model have no much more importancernto clearly register and manage the property of individuals. Due to unregistered 3Drnobjects(Building), individual property has no security, illegal settlements inside the town andrnaround the town increasing time to time, financial institution has no grantee for mortgaging for thernindividual properties. The aim of this research is to develop 3D Cadaster Data Modeling in casernstudy in Adama in order to digitally represent real property ownership rights, restrictions, andrnresponsibilities (legal models) and their physical counterparts to secure individual property andrncontrol illegal settlements inside the town and around the town. The methodology used to developrnthe 3D Cadastral Data Modeling was based on the data-modelling development cycle using EntityrnRelationship (E-R) Model techniques/method in this research and the top down approach was alsornused for data modeling. The data-modelling development cycle method was, gathering thernrequirements of 3D cadaster data (Business Analysis) from the real world, conceptual datarnmodeling of 3D cadaster, logical data modeling of 3D cadaster and physical data modeling of 3Drncadaster. The software used in this research thesis was, ArcGIS 10.3, Visio 2016, Object orientedrnprogramming language. After the requirement gathered from real world, conceptual, logical andrnPhysical data model were modeled for the implementation of 3D cadaster in Adama Townrndeveloped different data entry for fully implementation of the 3D cadaster.