Colonic diverticulosis has continuously increased, noticeably left-sided disease. Colovesical fistula is an uncommon complication of diverticulitis, and its most common cause is diverticular disease. Pneumaturia and fecaluria are commonly related symptoms. We present the case of a 79-year-old woman complaining pneumaturia and fecaluria. Abdominal CT showed a colovesical fistula due to sigmoid diverticulitis. After surgical adhesiolysis between the sigmoid colon and the bladder, the defect of the bladder wall was repaired by simple closure. The colonic defect was treated by segmental resection including the rectosigmoid junction. Following the operation the patient continuously improved at months 6, 12 and 18 without evidence of recurrences.