Documents in a traditional PDM(Product Data Management) system have been managed in a form of scanned document files or electronic documents developed by specific tools. Though each tool manages documents with its own systematical methods, it has drawbacks in data search, data integration and interchange, etc. For this reason, in this research we propose an efficient document management system for PDM by using the SGML(Standard Generalized Markup Language), one of CALS and ISO standards for document interchanges. Among documents to be managed in PDM, the engineering change notification (ECN) is taken into account. The DTD (Document Type Definition) has been constucted based on the logical analysis of the documents format, In addition, based on the DTD, DB classes have been designed by object-oriented paradigms and a prototype for document input/output and search has been developed using UniSQL ORDBMS (Object-Relational DBMS) and PowerBuilder under the client/server environment.