Inclusion Criteria:  Estimated glomerular filtration rate (Bedside Schwartz formula) of < 60 ml/min/1.73 m2 (stage 3, 4 and 5 CKD) for dialysis or non-dialysis patients. For ESA-naïve patients, mean of two most recent central laboratory Hb values during the screening period obtained at least 2 days apart must be < 11.0 g/dL. For patients currently receiving stable ESA dosing who will discontinue ESA and convert to roxadustat during study, mean of two most recent central laboratory Hb values during the screening period obtained at least 2 days apart must be ≥ 9.0 g/dL and ≤ 12.5 g/dL Ferritin >50 ng/mL and transferrin saturation >10%  Exclusion Criteria:  Uncontrolled hypertension as judged by the principal investigator prior to screening. Known hematologic disease related anemia (including PRCA) Known malignancy within the past 5 years before screening. History of severe anaphylaxis or known allergic to ingredient of roxadusta. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 3x upper limit of normal (ULN) and total bilirubin (Tbili) ≤2x ULN(obtained from screening visit). Serum folate and vitamin B12 > LLN and cannot be corrected (obtained from screening visit). Any RBC transfusion during the past 4 weeks before screening. Weight<10kg Any prior exposure to roxadustat or any other HIF-PH inhibitor.