Thoracoscopic repair of congenital diaphragmatic hernia (CDH) has recently become more common, and the challenge of managing neonatal cases is increasing. Meanwhile, there have been reported intraoperative complications or conversion to open surgery due to injury of herniated viscera and inability of organ reduction. We used the endoscopic surgical spacer SECUREA™ (Hogy Medical Co., Ltd., Tokyo, Japan), which is an elliptical sponge made of polyurethane with a radiopaque marker, for preventing these complications in three cases of CDH. The first case was a late presentation in a 10-month-old girl, and the second and third cases were prenatally diagnosed female neonates without severe pulmonary hypertension. All cases were left-sided hernias without sacs. At operation, the SECUREA was grasped using forceps, and the viscera were pushed back gently to avoid injuring the spleen or the short gastric vessels in the second and the third case. The SECUREA was intended to prevent intestinal injury during defect repair in all cases, with placement of the SECUREA between the edge of the diaphragm and the reduced intestine. The procedures in all patients were completed with no complications and without the need for conversion.