A 77-year-old woman who was treated for malignant melanoma was incidentally found to have a bladder tumor on a screening computed tomography (CT). On CT and magnetic resonance imaging (MRI), the tumor was detected as a well-enhanced tumor (4 x 5 cm at horizontal plane) on the left side of the bladder wall. Cystoscopy revealed a small non-papillary pedunculated tumor on the posterior wall and a submucosal tumor on the left side of the wall. We performed transurethral resection of the tumor on the posterior wall and biopsy of the tumor on the left side wall. The pathological diagnosis was paraganglioma of the urinary bladder. Serum and urine levels of noradrenaline and dopamine were elevated. 123I-metaiodobenzylguanidine (MIBG) scintigraphy showed a significant uptake on the left side of the bladder. Blood pressure was normal at rest but elevated after micturition. No pelvic lymph node swelling or distant metastasis was detected. We performed partial cystectomy for the tumor on the left side wall. After operation, serum catecholamine level was normalized and post-voiding fatigue that was present before operation disappeared. Six months after operation, a followup CT revealed a small well-enhanced tumor on the anterior wall of the bladder. Her serum noradrenaline level was slightly elevated. However, she was normotensive and had no symptoms. Therefore, a careful follow-up continued for 2 years there after has revealed no increase in tumor size and no symptoms.