: High purity niobium (Nb, 41) widely use to make a SRF (Superconducting Radio Frequency) as a superconducting material. Niobium purity that represented by RRR (Residual Resistivity Ratio) is very important factor in superconducting accelerator field. Usually, Niobium has between RRR 200 ~RRR 300 use to make the main body of SRF cavity. Niobium of RRR 50 which named as reactor grade use to make supporting structure of the cavity. Now, there are four big company to produce high purity niobium: ATI, Tokyo-denkai, Heraeus and Ningxia. All of the niobium sheet of QWR (Quarter Wave Resonator) and HWR (Half Wave Resonator) for RISP (Rare Isotope Science Project) is making by ATI. ATI is providing niobium sheet which meet requirement of electrical, mechanical and chemical properties with certificates. There is value range of each properties because the manufacturing company cannot make niobium which has completely same properties. The properties were analyzed regarding of the portion of specific Nb piece by specific RRR value and relationship between RRR value and other properties.