Tool embodiment is well recognized concept and commonly utilized as an explanation for the achievement of learning for tool use in sports activity and some specific skill in our life. Long-lasting use of prosthesis can be regard as the process of tool embodiment, and the extent of embodiment might have relevance to an affinity and comfortableness with the prosthesis. We are trying to develop different types of hand prostheses based on distinct two different elements of the process of embodiment, those are, (1) prosthesis as a part of body and (2) as a tool. We hypothesize that high function might facilitate to possess a sense of agency with prosthesis while a realistic appearance of cosmetic hand might lead embodiment of the artificial hand as a part of body, and lead to possess a sense of ownership with prosthesis. In my talk, I briefly describe concepts and rational behinds of our developed prostheses.