A 74-year-old woman visited our hospital complaining of pain in the left lower quadrant of the abdomen. Physical examination revealed tenderness to palpation without peritoneal signs. Blood test results showed elevated inflammatory response. Both ultrasonography and computed tomography revealed an intra-abdominal abscess containing a foreign body (fish bone) immediately below the left inferior abdominal wall. Lower gastrointestinal endoscopy conducted under fluoroscopic guidance revealed no intraluminal lesion in the colon adjacent to the abscess, and contrast examination also revealed no communication between the colon and the abscess. Fasting and administration of antibiotics did not improve the symptoms. We planned surgical procedure. Partial resection of the sigmoid colon was performed because of the presence of strong adhesions between the colonic wall and abscess. The postoperative course was uneventful, and the patient was discharged on hospital day 12. Histological examination of the resected specimen showed chronic abscess formation, but no communication between the intestinal tract and abscess. Onset was thought to be chronic in this case, because of uncertainty about the history of ingestion of fish bone and failure to verify any communication with the intestinal tract.