Abstract
It is needed for next generation of CAD system to be able to handle various types of design information and to be used from initial conceptual design stage. The purpose of this study is to construct a supporting system to assist the designers' mechanism creation processes. First, requirements for the mechanism are classified into two; those are "requirement related to behavior" and "requirement related to constraint", "requirement related to behavior" is composed by I/O relation, element of shape, and principle of behavior. Therefore, these elements and constraint are introduced for explaining the mechanism. Then, these four elements are analyzed by using mechanism handbook. Finally, requirements for supporting system are described.