X‐ray photoelectron spectroscopy (XPS) has been applied to characterize the damage introduced into SiO2by ion implantation. By measuring the peak width of Si2pfrom SiO2which corresponds to perturbation of the SiO2network, good depth profiles of the damage have been obtained for implanted samples and subsequently annealed samples. The results show that the damage distributed more widely than that calculated from energy deposition and that the perturbation of the network is caused not only by radiation damage but also by the existence of impurities in the network. It has been found that the XPS method is effective to understand the atomic structure, and thus, electrical properties of SiO2.