A measurement method for PVT properties of high-temperature and high-pressure gases was developed by simplifying the Burnett method and revising the data acquisition procedure. Instead of a differential pressure transducer, which is traditionally used, an absolute pressure transducer is used in the present method, and the measurement of pressure becomes easier. However, the absolute pressure transducer is placed outside the constant temperature bath because of the difficulty of its use in high-temperature surroundings, and some parts with different temperatures from the sample vessels exist as dead space. The present method takes into account the effect of the dead space in the data acquisition procedure. Nitrogen was measured in the temperature range from 353 K to 473 K and at pressures up to 100 MPa to determine the apparatus constants, and then, hydrogen was measured at 473 K and up to 100 MPa. The determined densities are in agreement within uncertainties of 0.07% to 0.24% (k = 2), both with the latest equation of state and existing measured data.