Internal hernias itself is not so rare, but considering individual cases, there are many unusual ones, preoperative diagnosis is difficult and treatment may be delayed. It is important to prevent the necrosis of the small intestine and to have a good postoperative course by performing diagnosis and surgery as soon as possible. I cited the anatomical structure, features on the image, and the treatment throughout the internal hernia, so I hope it will be useful for treatment of internal hernia. The case of foramen of Winslow hernia presented is very unusual, as the small intestine in the hernia passed through the foramen from left to right. The foramen of Winslow hernia is deemed unnecessary to close the hernia orifice, but in comparison with other internal hernias, or considering previous reports on the foramen of Winslow hernia, closure of the hernia orifice is necessary.