We report a case of prostatic cystadenoma. A 81-year-old man visited our hospital with the chief complaint of urinary difficulty. RUG and DIP showed bladder and prostatic urethra deviated to the left side. TRUS, CT and MRI revealed multilocular cyst in the pelvic cavity. Resection of the cystic wall was performed under the diagnosis of pelvic cyst. The cysts were originated from the right side of the prostate and adhered with the bladder severely. The histopathological diagnosis was prostatic cystadenoma. Fortyfive cases of prostatic cyst in the Japanese literature are reviewed.