The risk of foreign body by small button-disc battery in children has been increasing because the batteries are widely used in electronic device and plaything and easily contact with children. Foreign body of mercury type button-disc battery, when lodged in the esophagus, leak a caustic solution which causes a rapid necrosis of esophageal mucosa. So it should be removed immediately when the radiologic diagnosis is made. We experienced a case of esophageal foreign body by mercuric disc battery in a 14-month-old male. This case will be discussed with literature review.