It has become a common practice to reuse validated software components to shorten development periods and to increase the software quality. Component-based development is an effective reuse technology which extensively utilizes object-oriented design (OOD). Therefore, it is an economical approach to generate component-based design (CBD) from OOD. In this paper, we propose techniques for transforming OOD into CBD using Object-Z specifications. We first show how the structural, functional, and dynamic aspects of OOD can be specified in Object-Z. Then, we also present formal specifications of CBD in Component-Z, which is based on Object-Z and used to specify CBD. Using formal specifications of both OOD and CBD, we propose a set of rules for transforming OOD into CBD. By using our approach, OOD can be reused in generating CBD and the resulting CBD can be effectively implemented by utilizing objects in EJB, .NET, or CORBA. Also, this research provides a foundation for automating the transformation of OOD into CBD.