A 16-month-old boy swallowed accidentally a button type lithium battery with diameter 23 mm. The battery impacted at the upper esophagus was removed by endoscpy in 9 hours. At the time of removal, dark-crust and erythematous mucosal lesion was noted where the battery impacted. At the first hospital day, fever over 38.5 degrees C developed, and NPO, antibiotics and H-2 blocker started. At the third hospital day, he had melena, and endoscopy revealed huge active esophageal ulceration ranging from upper esophagus and lower body of the esophagus. Steroid started. At the 10th hospital day, endoscopy revealed much smaller-sized ulceration, but mucosa where the battery impacted initially showed deep depression which might imply developing diverticulum. At the 17th hospital day, endoscopy revealed complete diverticulum. At the 27th hospital day, endoscopy revealed complete resolution of diverticulum.