Interstitial pneumonia is a common and major comorbidity affecting the prognosis of patients with systemic sclerosis (SSc). However, there are few reported cases of SSc-rheumatoid arthritis (RA) overlap-associated interstitial pneumonia. We herein report a case in which the clinical behavior and histopathology of interstitial pneumonia with SSc-RA overlap syndrome was followed over a long clinical course. When clinicians are deciding on the treatment strategy for patients with SSc-RA overlap syndrome-associated interstitial pneumonia, a pathological examination of a surgical lung biopsy may be useful.