An object of the present invention to provide an agent for promoting the self-renewal of the neural stem cells and a method of using the same. ECF-L contained in a culture supernatant of endothelial progenitor cells derived from bone marrow has an effect of promoting the self-renewal of neural stem cells. Accordingly, ECF-L can be used as an ingredient of an agent for promoting the self-renewal of the neural stem cells, a pharmaceutical composition for growing the neural stem cells, and a pharmaceutical composition for treating a disease associated with neural dysfunction.
