Scheduled piecemeal resection has been actively conducted for granular type laterally spreading tumor (LST-G) in Japan, as long as a definite preoperative diagnosis is made. However, en bloc resection is desirable for depressed lesions (e.g. IIc lesion) as well as non-granular type laterally spreading tumor (LST-NG) since they have considerable high risk for submucoasl invasion and require precise histopathological evaluation. Endoscopic submucosal dissection (ESD) has been developed for the en bloc resection of mucosal tumors of gastrointestinal tract and widely applied especially in gastric lesions. Although the large intestine involves structural and technical difficulties, we conducted en bloc resection by ESD while exercising sorts of ingenuity for preparation; endoscopes, instruments, local injections, and others. ESD is a reliable technique that allows en bloc resection of gastrointestinal mucosal lesions, and even has a splendid possibility for the treatment of early stage colorectal cancer.