Spinal cord injury (SCI) is a catastrophic condition associated with significant neurological deficit, social, and financial burdens. Over the past decades, various treatments including medication, surgery, and rehabilitation therapy for SCI have been performed, but there were no definite treatment option to improve neurological function of patients with chronic SCI. Therefore, new treatment trials with stem cells have been studied to regenerate injured spinal cord. Among various types of stem cells, bone marrow derived mesenchymal stem cells is highly expected as candidates for the stem cell therapy. The result of the current research showed that direct intramedullary injection to the injured spinal cord site in subacute phase is most effective. Neurological examination, electrophysiologic studies, and magnetic resonance imaging are commonly used to assess the effectiveness of treatment. Diffusion tensor imaging visualizing white matter tract can be also alternative option to identify neuronal regeneration. Despite various challenging issues, stem cell therapy will open new perspectives for SCI treatment.