For cell-based therapy, it is necessary to obtain sufficient cell quantities for cell transplantation to the diseased or injured site. However, a given tissue has only a limited number of stem cells, making it necessary to expand stem cell source through long-term culture. In this study, we evaluated whether our recently described skeletal muscle-derived neural precursor (SMNP) cells can be cultured long-term without alteration of their neural precursor characteristics. Our results showed that SMNP cells can be cultured over approximately 16 months, but their growth rate and neurogenic potential gradually decrease in a culture time-dependent manner. Importantly, approximately 120-day cultured SMNP cells retain their self-renewal ability, neural precursor characteristics, and high neurogenic potential. These results suggest that SMNP cells may be an appropriate cell source for regenerative or reparative therapies against neuronal disease.