A 61-year-old man presented with an asymptomatic intrapelvic retrovesical tumor, measuring 8.5 cm in maximum diameter, which was revealed by preoperative diagnostic imaging for transverse colon cancer. When he was referred to our department one year after hemi-colectomy, this tumor showed no change in size, but there was some suspicion of concomitant malignancy because of large tumor size and contrast enhancement in a region adherent to the right seminal vesicle. En-bloc resection of the tumor along with the right seminal vesicle was performed retroperitoneally. The tumor was diagnosed histopathologically as retroperitoneal ganglioneuroma. Herein, we report this rare case of intrapelvic retroperitoneal ganglioneuroma, and present a brief review of the relevant literature including the present case.