Systemic sclerosis is characterized by tissue fibrosis, obliterative microangiopathy and immune abnormalities. The etiology of SSc is largely unknown and is known to be resistant to existing corticosteroid and immunosuppressive drugs. Therefore, establishment of a treatment strategy especially for SSc patients with organ involvement is strongly desired. Mast cells are widely recognized as effector cells in allergic disorders and other IgE-mediated immune responses. However, recently, mast cells have become known to play a role in bridging innate immunity and adaptive immunity. Additionally, there is growing evidence of mast cell to be involved in pathogenesis of rheumatoid arthritis, and is expected as a novel therapeutic target. We describe here the role of mast cell in SSc pathology and suggest as a novel therapeutic target.