The present disclosure relates to a database (DB) synchronization apparatus of a transmission network system which includes a plurality of network elements (NEs) and an Element Management System (EMS). Each of the NEs may include a common memory in which DB information and alarm state information are rearranged and a sync-related memory of the same pattern as the common memory for maintaining DB identity with the EMS. The EMS may include a EMS sync-related memory for storing the DB and the information of the sync-related memory of the plurality of NEs, and a EMS common memory corresponding to the common memory (CM) of the NE. A common memory which reflects database information and the current alarm information to the NEs, and a sync-related memory which stores data prior to a T-second period are built on the NEs, and these two memories are compared in block units to thereafter transmit only modified block data to the EMS. Accordingly, there is the advantage that since synchronization is established by the comparison of the memories, an initialization execution time is very fast, and a real-time data monitoring and management is convenient.