Silver ion conduction in beta-AgI single crystal along a c-axis was studied by impedance spectroscopy in the temperature range between 26-360 K. Anomalies were observed at similar to 40 and similar to 200 K in the data of the real part of the complex conductivity and at similar to 200 K in the imaginary part. Data analysis shows that the frequency-dependent complex conductivity in the frequency range below similar to 160 K and above similar to 220 K can be interpreted well by the Bernasconi’s random barrier model, Through the temperature range between similar to 160 K and similar to 220 K, ordering of Frenkel defects may occur above similar to 220 K.