Phase III Clinical Trial of NPB-01maintenance Therapy in Patients With Multifocal Motor Neuropathy.

Inclusion Criteria: * 1\. Patients who need high-dose intravenous immunoglobulin（greater than or equal to 1g/kg） therapy. * 2\. Patients who continued treatment for MMN without addition or increase at 30 days before informed consent. * 3\. Patients who MRC score increased 1 stage in greater than or equal to 2 muscles and not decreased relative other muscles to before at after in high-dose intravenous immunoglobulin therapy. * 4\. Patients with greater than or equal to twenty years old at informed consent. Exclusion Criteria: * 1\. Patients treated with Plasmapheresis at 3 months before informed consent. * 2\. Patients treated with Rituximab or Natalizumab at 6 months before informed consent. * 3\. Patients treated with Interferon-beta at 6 months before informed consent. * 4\. Patients treated with high-dose intravenous immunoglobulin（greater than or equal to 1g/kg） at 8 weeks before informed consent. * 5\. Patients treated with intravenous immunoglobulin at 3 weeks before informed consent. * 6\. Patients with history of shock or hypersensitivity for NPB-01. * 7\. Patients with IgA deficiency. * 8\. Patients with malignancy. * 9\. Patients with impaired liver function. * 10\. Patients with impaired renal function. * 11\. Patients with cerebro- or cardiovascular disorders. * 12\. Patients with high risk of thromboembolism. * 13\. Patients with hemolytic/hemorrhagic anemia. * 14\. Patients with decreased cardiac function. * 15\. Patients with decreased platelet.