Laparoscopic fundoplication is the current standard operation for gastroesophageal reflux disease and achalasia. An esophageal bougie is often placed for constructing a wrap or performing myotomy easily during the operation. The surgical complications reportedly include hemorrhage, esophageal perforation, gastric perforation, and vagus nerve damage. However, to the best of our knowledge, there is no report of any case of esophageal bougie misinsertion into the lower esophageal mucosa. The patient was a woman in her 50s who underwent laparoscopic Heller-Dor operation for achalasia in April 2007. During myotomy, we encountered difficulty in inserting a 56Fr-bougie and eventually realized that we had misinserted the Endolumina through the pyriform sinus into the esophageal mucosa. As the pyriform sinus injury was limited to the mucosa and there was no evidence of mediastinal perforation as assessed by intraoperative endoscopic examination, we continued the laparoscopic operation. On postoperative day 1, the patient complained of mild chest pain and pharyngeal pain, but there were only few signs of inflammation. Chest computed tomography revealed findings suggestive of a hematoma extending from the neck to the lower chest, most prominently in the right esophageal wall, however, the patient was followed up conservatively as there was no clear indication of perforation. Subsequently, both the chest pain and pharyngeal pain subsided. On postoperative day 5, the patient was allowed oral water intake, as a gastrografin swallow study did not indicate any problems. On postoperative day 6, the patient was allowed semiliquid foods orally. She was discharged from the hospital on day 11, without any particular problems. Currently, 10 months postsurgery, she is doing well, without any recurrence of symptoms such as dysphagia.