To characterize patterns of charges on electrets, Kelvin probe force microscopy (K FM) usually serves as a very useful tool to measure the electrostatic potential through an electric cycle; however, it is limited to electrets supported on conductive substrates. In this article, we demonstrate the use of atomic force microscopy (A FM) force mapping to visualize the pattern of charges on SiO2 electrets. In contrast to K FM, A FM force mapping can be used for characterizing electrets that are formed not only on conductive substrates but also on nonconductive substrates. Functional groups can be introduced to the A FM tip to achieve the force mapping and to improve the resolution. Our study clearly indicates that AFM force mapping can serve as an optional method for the characterization of electrets.