Submucosal injection is the most important procedure for the safe performance of endoscopic mucosal resection in the large intestine while avoiding the risk of perforation. We used dilute sodium hyaluronate containing Bosmin and achieved safe piecemeal resection of large superficial tumors in the right colon in two patients. Piecemeal snare resection is considered to be acceptable if all the tissue pieces can be collected for histopathological diagnosis.