Spectral diffuse reflectance and radiance factors of pressed polytetrafluoroethylene (PTFE) powder produced in Japan have been measured with variation of density, thickness, surface roughness, wavelength and ageing effects of the pressed powder. The 0°/d spectral diffuse reflectance was measured over 250 to 2500nm region. The radiance factors were measured at 0°and 45°incidence and at-80°to 80°viewing angles, on wavelength of 400nm, 550nm, 700nm, using an absolute goniophotometer. It has been found that, although slight ageing effects and weak fluorescence in UV region are recognized, the newly pressed powder has high reproducibility on diffuse reflectance and radiance factors under a certain range of pressing condition, and that the pressed powder will be useful for the radiance factor's standards as well as the diffuse reflectance standards.