A large ship usually consists of 300 to 500 blocks, for which it is extremely difficult to monitor the whole manufacturing processes from assembly to erection. In an effort to unify all the data and procedures, shipbuilding companies are installing ERP systems, which have brought great improvement throughout the company as a whole. In some departments, however, the ERP systems are not being fully utilized. This paper analyzes and solves the problems revealed especially at the production departments after an ERP system is installed. In this research, firstly a TOC(Theory of Constraints) analysis is done to find out the best solution for those problems. Secondly, based on the solution found, a Monitoring System for hull construction processes is developed with an improved user interface. The visualization of data is designed to reflect the needs of the production departments. The new system supplements the ERP system in that it selectively utilizes the unified data base and is operated under ERP environment. The system is installed in the production departments and its usefulness is verified.