A 42-year-old man visited a community hospital with chief complaints of lumbago and dyschesia. Computed tomography (CT) showed multiple lung, lymph node, and bone metastases and the irregular enlarged prostate with urinary bladder invasion. Serum prostate-specific antigen (PSA) was 544.0 ng/mL. Histological evaluation showed adenocarcinoma with the Gleason score 5 + 4, and the clinical stage was T4N1M1c as an initial diagnosis. Although androgen deprivation therapy was performed immediately, he had castration-resistant PCa after 3 months. Therefore, he received 6 courses of docetaxel chemotherapy every 3 weeks. Serum PSA was decreased to 0.2 ng/mL, and multiple metastases and prostate size were obviously reduced based on CT. He underwent robot-assisted radical prostatectomy and radiation therapy for prostatic fossa and multiple metastases. Although serum PSA level remained low, CT showed multiple liver metastases after 3 years from surgery. He received the combination therapy of cisplatin and etoposide (PE) every 4 weeks. Liver metastases had complete response. However, he visited our hospital with complaint of vomiting and a right drooping eyelid after 6 weeks from withdrawal of PE therapy. T2-weighted magnetic resonance imaging revealed multiple leptomeningeal metastases (LM). He received RT for the brain and was administered amrubicin. However, he died of PCa after 6 weeks from the diagnosis of LM.