We evaluated the accuracy of the point diffraction interferometer, which has been completed at the Atsugi Research Center's Association of Super-Advanced Electronics Technologies for the precise measurement of extreme ultraviolet lithography optics. To evaluate the absolute accuracy, more precision is required. A pinhole with 0.5 mum diameter was used to generate a near completely spherical reference wave front, and helium gas filled the inside of the chamber to suppress air turbulence. With this apparatus, precision of 0.04 nm root-mean-square (rms) was achieved. Absolute accuracy was evaluated from the measurement of mirror rotation and displacement and an absolute accuracy of 0.17 nm rms was obtained for a spherical mirror with numerical aperture of 0.145. Absolute accuracy was improved to 0.11 nm rms by limiting the numerical aperture to 0.08.