Abstract: A support device for a computer aided design system to improve efficiency in design work by achieving automatic recognition of associated design programs and automatic data transfer between the steps of a process of design, comprises a first, a second and a third design applications to be executed independently, a first, a second and a third design data bases to be called out by the design applications, and a management part connected to the data bases for managing the entire process. A design structure management file of the management part manages a hierarchical structure of the objects of design and when a modification of contents of design is made to one of the applications specifies a part or parts to which the modification is to be reflected. An identification file of the management part decides a direction of data transfer between the applications.