Authors have been engaged in development of SODAS for shipbuilding CIM. The product definition system considered in SODAS is now recognized to be very effective to implement to design system and manufacturing system. One of the most significant issues in assembly industries is accuracy control of products, because accuracy control is deeply related with manufacturing efficiency and cost. Therefore in this paper, accuracy analysis is carried. Two types of modules are considered. One is assembly module, and the other is measured module. When a measurement is carried for special points on assembly module, the implemented system describes these measured values in measured module. Furthermore authors make clear the function by which difference evaluation between assembly module and measured module can be done.