The treatment effects of metastasis-directed therapy in patients with oligometastatic disease have received much attention. In our case, a 72-year-old man with oligometastatic castration-resistant prostate cancer was referred to our hospital. The patient had undergone radical radiotherapy with a total dose of 76 Gy in 36 fractions for localized prostate cancer nine years prior to the first visit. Positron emission tomography showed a slight increase in accumulation in the para-aortic lymph nodes. The patient received conventional radiotherapy at a total dose of 50 Gy in 25 fractions to the para-aortic region as oligometastasis-directed local therapy. After radiotherapy, his prostate-specific antigen (PSA) level decreased slightly, but it increased again soon after. According to the results of positron emission tomography, the accumulation around the para-aortic lymph nodes had decreased; however, a slight increase in accumulation in the sub/supra-clavicular lymph nodes was observed. He received radiotherapy at a total dose of 50 Gy in 25 fractions to the sub/supra-clavicular region. We confirmed a significant reduction in lesion volume and a downward trend in PSA levels. Metastasis-directed therapy has shown remarkable effectiveness in controlling disease without severe treatment-related adverse events. Metastasis-directed therapy is considered as one of the treatment options in patients who need salvage therapy.