We report a 17-year-old boy who was diagnosed as autoimmune encephalitis with various neurological complications such as hemiplegia, aphasia and seizures. An autoimmune process was considered to be responsible for the repeated episodes of encephalitis because the symptoms were highly responsive to steroids and anti-glutamate receptor antibodies were detected in the CSF. After administration of the immunosuppressant tacrolimus, we could taper the steroid dosage. He has had no relapse for three years to date. We demonstrated the possibility of steroid-sparing treatment with tacrolimus for a patient with steroid-responsive encephalitis. There were few reports describing tacrolimus therapy for encephalitis. Tacrolimus may be effective for selected patients with recurrent encephalitis in which an autoimmune mechanism is considered as the pathogenesis.