A 47-year-old woman who was diagnosed as progressive systemic sclerosis (PSS) had acute and severe interstitial pneumonia. Based on the results of her chest roentgenogram, computed tomography, transbronchial lung biopsy (TBLB) and bronchoalveolar lavage (BAL), her interstitial pneumonia was considered to be atypical of PSS. Although she was treated with corticosteroid, methylprednisolone pulse therapy and immunosuppressive drug, the effect of these drugs was insufficient as treatment for the interstitial pneumonia. Therefore, plasma exchange was attempted. After plasma exchange was carried out for three days, her symptoms improved as well as the laboratory data and chest roentgenogram without any severe side effects. We recommend plasma exchange for interstitial pneumonia of PSS as an effective treatment.