It is sometimes difficult to diagnose phlegmonous gastritis clinically. We herein present a rare autopsy report of a patient with phlegmonous gastritis associated with nonalcoholic steatohepatitis-related cirrhosis. The patient died of hepatic failure two weeks after exacerbation of anorexia and rapid progression of liver dysfunction. Autopsy revealed cholangitis lenta and sepsis-induced liver dysfunction, which was attributed to phlegmonous gastritis due to Moraxella (Branhamella) catarrhalis. Phlegmonous gastritis has seldom been reported in patients with liver cirrhosis. We believe the importance of keeping in mind that phlegmonous gastritis could be one of the complications of advanced liver cirrhosis.