A human motion synthesizing system has been developed for generating various kinds of human motions flexibly as 3 dimensional computer graphics in virtual environment. This system is designed based on the idea derived from the concept of affordance. The idea is that the entire algorithms and the information necessary for synthesizing a human motion should be composed in the object database which is an archive for the virtual object¡Çs information. This design methodology makes it possible to make a new algorithm for synthesizing a human motion available without reconstructing the human motion synthesizing system. In this paper, how to apply the concept of affordance to design the human motion synthesizing system and the overall configuration of the developed system are described.^M