Master data provides business consistency and data integrity to different data systems when multiple IT systems across an organization (or beyond) identify the same entity differently. Master data can support transactional processes and operations. In addition, analytics/reporting are another area greatly dependent on an organization's master data. Therefore, master data represents core information, and organizations should consider it to be an important asset. Building a structure of each master data and representing an integrated data model are the main tasks of master data management. However, most research thus far has concentrated on data flow and data standards for building the physical environment of a centrally controlled master data management system. Only partial logical models with specific entities have been suggested, even for a master data model. This paper suggests an enterprise master data model (EMDM) which defines all of the master data composition elements, the hierarchical structure in each master data element, and the relationship between master data elements across the organization. The origin data taxonomy methodology was adopted to represent the master data elements and hierarchical structure. A case study demonstrates the proposed enterprise master data model (EMDM) applied to an insurance business.