A 50s women underwent laparoscopic abdominoperineal resection(APR)for rectal cancer. Laparotomy was performed on the 8th postoperative day because of intestinal obstruction. An internal hernia was observed at the pelvic floor and the hernia orifice was found at the retroperitoneum that was sutured in the initial operation. On the other hand, the jejunum near the Treitz ligament was twisted, resulting in ischemic necrosis. The reason of the internal hernia is considered that a suction drain placed during the initial operation may have caused the rupture of the fragile part of the sutured peritoneum. Furthermore, increase of intra-abdominal pressure due to the internal hernia may have exacerbated the torsion of the jejunum near the Treitz ligament. This is probably due to the failure to the adequate reposition of the small intestine at the end of the initial operation. There is no consensus of the need for retroperitoneal sutures for APR. Currently, we only spray anti-adhesion agents on the pelvic floor without retroperitoneal reconstruction. Although the mobilization of small intestine is important to provide a good operative view in laparoscopic colorectal surgery, it is also important to confirm the reposition of the small intestine at the end of surgery.