We report a case of a 62-year-old man with secondary prostatic tumor, which manifested postrenal renal failure. Although pathological examination of the transurethral biopsy specimen and rectal biopsy specimen revealed no malignancy, transperineal prostatic biopsy specimen demonstrated signet ring adenocarcinoma. Post-mortem examination suggested that cancer cells had transferred from the stomach or the gallbladder to the prostate and other organs.