Inclusion Criteria:  Age > 18 yrs old RA diagnosed by ACR/EULAR 2010 low to moderate disease activity on stable NSAIDs and DMARDs for at least 1 month Received Prednisolone less than or equal to 7.5 mg/day serum calcium, phosphorus and ALP are within normal limit.  Exclusion Criteria:  Chronic kidney disease stage 3 or higher History of TB History of Chronic liver disease Pregnancy or breast-feeding adjustment of immuno-suppressive drugs, steroid other connective tissue disease Vitamin D allergy received other drugs which have vitamin D component serum Vitamin D less than 10 ng/mL