We herein describe the case of a 48-year-old woman who presented with nonconvulsive status epilepticus refractory to antiepileptic drugs caused by anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis without any tumors. She developed nausea and psychiatric symptoms, followed by fever and an acute progressive disturbance of consciousness. On admission to our hospital, she presented with involuntary orofacial movements and central hypoventilation, and an electroencephalogram showed a generalized slow activity consistent with nonconvulsive status epilepticus. The patient's drug-resistant status epilepticus markedly improved following second-line immunotherapy with rituximab and cyclophosphamide. Physicians should consider the early initiation of second-line therapy in certain cases of anti-NMDAR encephalitis.