Viscosity of hydrogen has been measured at high pressures and high temperatures by using capillary tube method. The measurement apparatus was designed specifically for high pressure gas up to 100MPa. The capillary used quartz glass tube 0.1mm in inner diameter and 400mm in length. The measurement range is 0.1MPa to 100MPa, and room temperature up to 723K. We have to generate laminar flow inside the capillary tube that is the range of Reynolds number from 250 to 900. Since we measured nitrogen gas viscosity at the same range and many nitrogen viscosity data have already been measured in these ranges, nitrogen data was used in this study to confirm the accuracy of our apparatus before measurements of hydrogen. The measurement results of hydrogen are evaluated compared with our existing correlation(Yusibani Correlation). The results of hydrogen viscosity agree well with the existing correlation within 2% except for the measurements at 723K. The relative uncertainty of the present measurement system is estimated to be as much as 2%.