In this paper, a rescheduling procedure is developed for shipbuilding master production schedule. Shipyard initially develops backward production schedules for the entire shipbuilding process, and then refines the schedule by stage. The rescheduling procedure of this paper tries to resolve the schedule discrepancies between the outdoor backward schedule and the refined indoor schedule. Through the proposed rescheduling procedure, outdoor schedule can be successfully adjusted using buffer days and duration reduction. An Object-oriented program is also developed to automate the procedure. We can observe the improvement on productivity and quality of rescheduling works from the application of the developed procedure.