The described research methods explain how you could generate a three-dimensional kidney, based on recent research results. The first method is to fabricate human organs in a pig body. The second is to transplant the so-called "organ bud" into a patient's body for further development. The third method is to regenerate organs by filling cells into the cytoskeleton as a scaffold. Research for the in vitro fabrication of organ buds has been elaborately accelerated. The organ bud transplantation has been confronted with issues of continuity with the original organs, so the development of technology for achieving continuity between a transplanted organ bud and the existing organs is progressing well. The "organ fabrication" methodology, whereby cells are placed into completely decellularized organs, is supported by recent research results using pig organs taking the size of humans into consideration.