We report a case of peritonitis resulting from colon perforation caused by ingestion of a rare foreign body in a patient on peritoneal dialysis (PD). A 72-year-old woman on PD was hospitalized with abdominal pain and cloudy PD fluid (PDF). Although conventional antibiotic therapy was started because of a diagnosis of infectious peritonitis, low-grade fever, abdominal pain and a high number of white blood cells in PDF persisted. On day 3, anaerobic bacteria were recognized on bacterial culture of PDF, suggesting a gastrointestinal etiology. During exploratory laparotomy, sigmoidal perforation by a piece of bamboo, probably resulting from ingestion of contaminated food, was found.