Rocuronium is the anesthetic agent most likely to cause anaphylaxis. Immediately after intravenous rocuronium administration, the authors experienced ventilatory impairment due to unilateral bronchospasm (left lung), which was relieved by emergency treatment. However, 80 minutes after beginning laparoscopic surgery for rectal cancer, the left lung suddenly re-collapsed under pneumoperitoneum in the Trendelenburg position. A postoperative intradermal test revealed that rocuronium, vecuronium, atracurium, succinylcholine, or thiopental could induce anaphylaxis in this patient, but it was not established whether the second incident during surgery was due to endobronchial intubation or anaphylactic bronchospasm. This case cautions that under pneumoperitoneum in the Trendelenburg position, patients suspected of being prone to anaphylactic bronchospasm should also be considered at risk of endobronchial intubation.