PROBLEM TO BE SOLVED: To provide an undifferentiation-maintaining and growth-promoting agent for stem cells which exhibits a stem cell-specific growth-promoting effect while maintaining an undifferentiated state of stem cells of mammalian animals, a stem cell having a high survival rate to tissues at transplanting, and a technology for preparing the same.SOLUTION: Specific growth of stem cells is promoted while maintaining an undifferentiated state of stem cells by using an extract from fungus gall of Zizania latifolia for embryonic stem cells of mammalian animals, somatic stem cells in body tissues such as bone marrow, blood, fat and skin tissues, or artificially prepared stem cells. Further stem cells prepared in a culture solution containing the extracts have an improved effect on a survival rate to body tissues at the transplanting. Therefore, this technology can contribute greatly to the field of tissue regeneration and is expected to be applied to medical, pharmaceutical, quasi drug, cosmetic and health fields.
