A 62-year-old man was admitted to our hospital complaining of sore throat and epigastralgia. Laboratory tests revealed leukocytosis and an elevated CRP level. CT showed a low density area in the right hypopharynx, wall thickening of the esophageal and gastric wall with an intramural low density area. Phlegmonous esophagogastritis associated with hypopharyngeal abscess was diagnosed. The infection was extension and his condition was serious because of his accompanying poorly controlled diabetes. He was successfully treated by antibiotics and drainage of the hypopharyngeal abscess. CT was useful for early diagnosis, confirmation of the extent of inflammation and follow-up.