Endoscopic submucosal dissection (ESD) is a standard treatment for early gastric cancer, but it is not generally used for colorectal lesions because of its high risk of adverse events. An unanticipated adverse event of rectal ESD is reported. A 71-year-old man was found to have a laterally spreading tumor at the upper rectum. ESD was performed. During the ESD, rectal perforation occurred, and emergency laparoscopic surgery was performed. At the operation, rectal perforation with retroperitoneal emphysema was detected. Surprisingly, an 8-cm-long, lacerated wound was found at the cecum wall. It was thought to have been caused by heat injury due to ESD. The perforated site was resected, and the laceration of the cecum was repaired by extracorporeal suture. In patients with perforation during ESD, it is essential to keep in mind that other organs might have heat-induced injury, and the patient should be more carefully followed