The rapid growth of international trade and world market has brought notable increases in casualties involving ship collisions and aircraft crashes. After years of trying to reduce such risks, there still remain the possibilities of those kinds of accidents. In these circumstances, this research discusses the limitation of shipowner`s liability for maritime casualties. And it specifically focuses on ship collisions involving towage with the related Korean Supreme Court`s decisions and the U.S. famous cases. Until recently, ship collisions involving tugs and barges often happen in the Korean sea area, so this study is very necessary at this point. The Korean Commercial Code Article 769 provides that the shipowner may limit her liability for the claims falling under any of the subparagraphs of Article 769 to the amounts as prescribed in Article 770, whatever the basis of liability may be, provided that the shipowner shall not be entitled to limit her liability if the loss resulted from her personal act or ommission,committed with the intent to cause such loss, or recklessly and with knowledge that such loss would probably result. Then the limitation amount shall be calculated on the basis of the tonnage of each ship which is responsible for the collision. Therefore, it is the most critical question in the calculation to decide which ship among tugs and barges should be selected for the tonnage criteria on the limitation of liability. The fact that barges themselves have no motive power for navigation always leads discussions. Because the ship collision is a type of tort, the liability in ship collision can arise when there is an intent to cause harm or negligence. In this respect, the ship whether it is a tug or a barge, which is responsible for the damage or has contributed to the loss, should be the very ship in Article 770. And each calculating sum under Article 770 should be added up in total. The Korean Supreme Court is also in the same position. Therefore, the limitation of shipowners` liability for casualties involving tugs and barges is summarized as determining which ship has supervisory or ultimate control power over the flotilla during the navigation. For this purpose, it should be carefully scrutinized that each ship has the duty to exercise such reasonable care and maritime skill as prudent navigators employ for the performance of similar service to abide by carriage rules or to avoid forseeable harm.