Inclusion Criteria:

• Patients diagnosed as generalized myasthenia gravis
• Patients who are not controlled by current therapy and need plasmapheresis therapy
• Patients who have the high-dose steroid therapy for over a month in past years, and also who take steroid or immunosuppressant on the day of consent
• Patients who had not any dose increase or new dosing of steroid or immunosuppressant within 4 weeks prior to enrollment

Exclusion Criteria:

• Patients who received steroid pulse therapy, globulin therapy or plasmapheresis therapy within 12 weeks prior to enrollment
• Patients who had undergone thymectomy within 24 weeks prior to enrollment
• Patients with 3 points item in bulbar symptom of MG-ADL scale
• Patients with severe hepatic disorder, severe renal disorder or severe heat disorder
• Patients who have received treatment of malignant tumors
• Patients who have the anamnesis of shock or hypersensitivity to this drug
• Patients who have been diagnosed as hereditary fructose intolerance
• Patients who have the anamnesis of cerebral infarction or symptom of these diseases
• Patients who have been diagnosed as IgA deficiency in their past history
• Pregnant, lactating, and probably pregnant patients, and patients who want to become pregnant
• Patients who were administered other investigational drug within 12 weeks before consent