In 2017, Korean Society of Medical Oncology (KSMO) published the Korean management guideline of metastatic prostate cancer. This paper is the 2nd edition of the Korean management guideline of metastatic prostate cancer. We updated recent many changes of management in metastatic prostate cancer in this 2nd edition guideline. The present guideline consists of the three categories: management of metastatic hormone sensitive prostate cancer; management of metastatic castration resistant prostate cancer; and clinical consideration for treating patients with metastatic prostate cancer. In category 1 and 2, levels of evidence (LEs) have been mentioned according to the general principles of evidence-based medicine. And grades of recommendation (GR) was taken into account the quality of evidence, the balance between desirable and undesirable effects, the values and preferences, and the use of resources and GR were divided into strong recommendations (SR) and weak recommendations (WR). A total of 16 key questions are selected. And we proposed recommendations and described key evidence for each recommendation. The treatment landscape of metastatic prostate cancer is changing very rapid and many trials are ongoing. To verify the results of the future trials is necessary and should be applied to the treatment for metastatic prostate cancer patients in the clinical practice. Especially, many prostate cancer patients are old age, have multiple underlying medical comorbidities, clinicians should be aware of the significanc