An adverse drug reaction (ADR) surveillance system integrated with various electronic medical record (EMR) systems has been suggested as an effective way to collect more data and analyze ADRs earlier than the spontaneous reporting of ADRs. Because Korean hospitals have heterogeneous EMR databases, a common data model (CDM) should first be defined to develop the multi-center EMR-based drug surveillance system. We investigated the data models from two prominent drug safety surveillance studies, the Mini-Sentinel program and the Observational Medical Outcomes Partnership, and developed an EMRbased ADR common data model (EADR CDM). The EADR CDM has eight tables, including a demographic table, drug table, visit table, procedure table, diagnosis table, death table, laboratory table and organization table. Each table consists of 5-12 fields. Among a total of 2,931,060 patients from January 2008 to December 2012 in clinical data warehouse of the S hospital, we extracted the data from 135,745 patients who were prescribed below drugs to determine whether the exported data were sufficient to detect ADRs of six drugs. After validation, we found that the transformed data based on EADR CDM is helpful to understand the prescription pattern and explore feasible medication list for adverse drug signal detection.The collection of diverse data using the CDM is an effective method of early decision of ADRs. This study provides guidelines for developing the CDM and plans to develop the drug safety surveillance system based on multi-center EMR.