Shipbuilding industry has long been devoting to complete CAD/CAM systems in the stage of design and fabrication. However it is often said even now that elaborating engineering works are needed to manage CAD/CAM systems. In recent years, the necessity of computer integrated manufacturing system in shipbuilding industry has been recognized in our shipyards. Ship research committee 210 of Japan Shipbuilding Research Assoiation organized the feasibility study of computer integrated design and manufacturing in 1987. In order to integrate CAD/CAM system, product modeling and expert systems were taken as the most important themes in the project. The aim of our paper is to propose one example of a product model of ship. The model should be as flexible as possible because it is used as a model not only in design stage but also in manufacturing stage. Object oriented concept is used to represent a ship model. Two types of objects are introduced in our paper. One is body object which states geometrical properties and its attributes. The other is connection object which states the connection relation of body object A with object B. Concepts of cutting of designed ship structure into pieces and assembling those pieces to a ship block are also introduced here. It can be said that the ship model proposed here can be used in the design and manufacturing stages.