In May 2009, a 57-year-old woman who had rheumatoid arthritis since 9 years was admitted to our hospital for dyspnea due to interstitial pneumonia (IP). On admission, she exhibited proximal scleroderma, finger edema, Raynaud's phenomenon, digital pitting scars, ankyloglossia, and esophageal dysmotility. The patient was diagnosed as having systemic sclerosis (SSc), according to the American College of Rheumatology criteria. After initiation of high-dose corticosteroid therapy, gradual amelioration of IP was observed. However, the patient complained of abdominal fullness. Computed tomography and intestine series findings revealed significant dilatation of the small intestine due to intra-abdominal free air and pneumatosis cystoides intestinalis but no mechanical obstruction, leading to a diagnosis of SSc with pseudo-obstruction. The patient underwent decompression with a long intestinal tube, which led to improvement in her symptoms. Although erythromycin (EM) and some prokinetic agents were administered, abdominal involvement recurred several days after resumption of oral ingestion. Therefore, we changed the antibiotic from EM to metronidazole (750 mg/day). Her manifestations were promptly ameliorated by metronidazole therapy in 4 days and did not recur. Metronidazole is an antibiotic used to treat intra-abdominal anaerobic bacterial infections and is also commonly used in preoperative treatment for colorectal surgery. In conclusion, we report a case where SSc-associated pseudo-obstruction was successfully managed by metronidazole therapy.