This randomized, double-blind, placebo-controlled multi-center study will carry out to assess the efficacy of GB-0998 in the treatment of the systemic sclerosis based on the changes in modified Rodnan total skin thickness score (TSS) as primary endopoint, and in addition, to assess the safety of GB-0998.

Inclusion Criteria:

• Patients who have sclerosis located proximal to the elbow joint with diffused systemic scleroderma.
• Patients who have not less than 20 points of TSS.
• Patients with no appropriate therapeutic treatment.

Exclusion Criteria:

• Patients with severe hepatic disorder, severe renal disorder or severe heart disorder.
• Patients with malignant tumors.
• Patients who have the anamnesis of shock or hypersensitivity to this drug.
• 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 had any dose increase or new dosing of steroid within 12 weeks before consent.
• Patients who were administered other investigational drug within 12 weeks before consent.