In December 2011, an 84-year-old Japanese man was admitted with severe cholecystitis. We treated the cholecystitis using antibiotics, and his symptoms improved. In March 2012, he was readmitted after experiencing a sudden bloating sensation and vomiting. We determined that a gastric wall abscess had protruded into the antrum. The gastric wall was adjacent to the gallbladder, and the gastric abscess was related to a known case of cholecystitis. Upper gastrointestinal endoscopy indicated that the abscess was under the mucous membrane of the gastric antrum. Pus, exuding from the abscess, was aspirated with an endoscope.