Carcinosarcoma is a rare malignant tumor of the urinary bladder. This tumor has a char-acteristic admixture of carcinomatous and sarcomatous components. We herein present a case of a carcinosarcoma of the urinary bladder in a 57-year-old woman. She visited our hospital be-cause of painless gross hematuria. A series of studies including intravenous urography, cystoscopic examination, and computed tomography revealed a large bladder tumor. Partial cystectomy was performed. Pathology proved it to be a carcinosarcoma.