The majority of small/medium sized shipbuilders in Korea is poor in capital and then, should be restructured as an efficient production system with low investment. Due to considering this situation, the cooperative work system is proposed, in this study, as more effective production system for small/medium sized shipbuilder The cooperative work system Is the production system that many small/medium sized shipbuilders in a group jointly share the common facilities except minimum equipments and have managerial cooperation such as joint purchase of raw materials. The efficiency of cooperative work system is proved from economic and technical point of view with the case study of FRP shipbuilders of Sapjin industrial complex located at Mokpo area.