The present invention relates to a method of converting human fibroblasts into neural stem cells, and more particularly, to a method of directly converting human fibroblasts into neural stem cells using only a combination of small-molecule compounds without any introduction of a foreign gene, and to the use of the neural stem cells. The method of directly converting human fibroblasts into neural stem cells using only small-molecule compounds without any introduction of a foreign gene makes it possible to obtain genetically stable neural stem cells in an amount sufficient for use in cell therapy by deriving them from human fibroblasts. The neural stem cells obtained according to the method of the present invention can differentiate into functional neural cells and are not tumorigenic. Thus, these neural stem cells are useful as cellular therapeutic agents for treatment of brain diseases.