There are many case reports on colon diverticula that cause irritable bowel syndrome, constipation, bleeding, diverticulitis, stricture due to multiple recurrences of diverticulitis, and perforation. However, few articles have examined neoplasms that arise from a diverticulum, such as adenoma and adenocarcinoma, and there have been no reports of granulation polyps that arise from a colon diverticulum after recurrent diverticulitis. We observed a rare granulation polyp that arose from a diverticulum as a result of repeated episodes of local diverticulitis. Narrow band imaging magnified colonoscopy was very useful to diagnose the polyp as a granulation polyp because of the absence of a pit pattern on the surface of the polyp. We successfully resected the polyp using endoscopic mucosal resection. We inverted the diverticulum, and the resected stalk of the polyp was used to close the diverticulum with an over-the-scope clip. If a granulomatous polyp could arise from a diverticulum, differential diagnosis between a colon neoplasm and a granulomatous polyp would not only be difficult but also necessary for suitable endoscopic treatment.