A 54-year-old Japanese woman with a 6-year history of systemic lupus erythematosus (SLE) was admitted to our hospital suffering from acute blindness in her right eye. Her condition recovered after steroid pulse therapy, however, 18 months later she suffered from nuchal pain for 2 weeks after which right hemiparesis with urinary incontinence developed. A spinal magnetic resonance imaging (MRI) revealed cord swelling from C2 to C7. She was diagnosed with neuromyelitis optica (NMO) and intravenous steroid administrations were immediately commenced. Her condition promptly improved. This case was unique because the steroid treatment was quite effective for this case of myelitis, which had passed the acute phase. We supposed that, because most of the lesion was not necrotic or demyelinated, but rather showed edematous change caused by vasculitis based on autoimmune pathogenesis, the symptoms progressed rather gradually and improved promptly in response to glucocorticoid treatment.