A study for the neutralization of charge-up potentials observed in monochromatized XPS analysis of α-alumina single crystal plate without electron flood gun was carried out. In order to reduce the very large charge-up potential of 470∼481 eV, when no neutralization technique was used, the alumina surface was masked with a thin gold film with a hole of 1∼7 mmφ. The charge-up potential strongly depended on the monochromatized X-ray flux and the diameter of the hole. It became smaller than +15 eV for both the focus and defocus modes of X-ray source with diameters of 2 and 5 mmφ of hole, respectively. These results indicate that exposure of the gold mask to X-ray flux is essential so that photoelectrons, Auger electrons, and secondary electrons emitted from the gold mask are supplied to the sample surface with charge-up potentials. Further, the relationships among charge-up potential distributions, X-ray flux distributions, peak height (and/or area), full width at half maximum of Al 2 p, and the difference in binding energy between O1 s and Al 2 p were elucidated.