Locoregional therapy for oligometastatic prostate cancer has generated great interest. However, the benefit for castration-resistant prostate cancer (CRPC) has not been fully demonstrated. According to the current study, whole body-MRI incorporating DWI identified a substantial number of oligo-progressive CRPC patients (OP-CRPC) with a number of progressive lesions 3 or less. Progressive site-directed therapy (PSDT) to OP-CRPC provided a high treatment effect in terms of prostate-specific antigen (PSA) response, especially for patients with longer PSA-doubling time. Furthermore, this study identified the site-dependencies of the PSDT treatment effect; patients whose progressive site was localized in the pelvis were good candidates for PSDT.