For the purpose of medical applications of a method for manufacturing human tissue/organs, the present invention provides an improved method with which functions per cell are considerably improved and a large-scale cost reduction is realized. A method for manufacturing organ buds according to the present invention includes in-vitro culturing of vascular endothelial cells, mesenchymal cells, or tissue or organ cells in the presence of blood cells. Also provided are: the organ buds manufactured by using the method； a method of manufacturing tissue or organs by using the organ buds； a method for transplanting the organ buds； a method for regenerating or recovering the functions of tissue or organs； a method for manufacturing non-human chimeric animals； and a method for evaluating drugs.
