Atomic structures of Ag2Te in the low- and high-temperature phases have been studied using a scanning tunneling microscope in air and an x-ray diffraction system. In the low-temperature phase having a monoclinic lattice, (001) and <(0(1)over bar 0)> atomic images are obtained. In the superionic high-temperature phase, which is stable at temperatures above 145 degrees C, (100) surfaces of the Te cubic lattice are observed. In both phases, surface atomic reconstructions are not detected.