We report a case of small intestine penetration by a fishbone with migration to the abdominal wall and abscess formation. A 40-year-old man visited our hospital with the chief complaint of a painful left lower abdominal mass for one week. An abdominal computed tomography (CT) scan revealed a foreign body located in the abdominal wall with abscess formation. An operation was therefore performed and a fish bone was retrieved. Foreign body ingestion should be considered as a rare cause of abdominal pain or abscess of the abdominal wall. A perforation of the gastrointestinal tract by an ingested foreign body is difficult to accurately and quickly diagn ose when no peritonitis is observed. CT scanning may provide a preoperative diagnosis and allow an appropriate therapeutic approach.