The objective of this study is related with an on-going project ¡ÇVirtual Collaborator¡Ç which is a sort of ¡Çvirtual robot¡Ç that behaves like human in virtual environment. In conjunction with the Virtual Collaborator Project, an experimental study was conducted with the purpose of exploiting more efficient method of natural human walking phantom. The study consists of cross-correlation analysis for a selected pair of body parts of the phantom¡Çs walk motion and subjective rating by persons observation by showing them various sets of phantom walking animation. Then, an efficient method of synthesizing animation of natural human walking is proposed.