Colonoscopy is used increasingly because the indication for therapeutic colonoscopy has been increased and the technique has been developed continuously as well as colonosopy is useful for diagnosis of colonic disease. Therefore, It is important understanding precisely about the complication of colonoscopy and managing the complication immediately and properly. In particular, colon perforation is the most fatal, emergency case and have needed surgical treatment, generally. Recently, the case treated with endoscopic clipping and conservative management has been reported. but until now, when perforated, wheather the endoscopic clipping or the surgical management at each other case is beneficial is not confirmed. (Intestinal Research 2004;2:21-25)