We report a difficult-to-diagnose torsion of the gallbladder with acute emphysematous cholecystitis. An 87-year-old woman was admitted to the hospital because of fever, appetite loss, nausea, and vomiting. The temperature was 37.8°C. On physical examination no jaundice was noted. The abdomen was flat, but there were tenderness and muscular gurding in the right hypochondriac region. Abdominal CT scan and abdominal ultrasonography revealed gas formation in the swollen gallbladder. Based on these findings, a diagnosis of acute emphysematous cholecystitis was made, and an operation was performed. At laparotomy, there was bloody ascites with bad smell below the right diaphragma, around the gallbladder, and the gallbladder was swollen, dark-red in color and twisted counter-clockwise by 270 degree. Then a cholecystectomy and drainage were performed. These findings suggest that circulatory dysfunction due to the torsion of the gallbladder caused acute emphysematous cholecystitis.