The electronic band structures of beta-alumina-type superionic conductors (SIC) are proposed and discussed using experimental results for the reflection and absorption spectra in the ultraviolet and vacuum-ultraviolet regions and photoemission spectra. The measurements were performed using beam Lines with synchrotron radiation. The valence bands of all beta-alumina-type SIC are constructed from the 2p orbital of oxygen (O 2p). In the case of alkali beta "-aluminas, the lowest conduction band is due to the s orbitals of alkali ions. It is concluded from this result that all conduction ions are not perfectly free, but construct bonds, giving rise to an ordered structure existing in a limited region. On the other hand, in the case of alkali beta-aluminas, this is due to the 3s orbital of aluminum. The low lying exciton bands due to the orbitals of Ag ions and due to the orbitals of Tl ions are observed in Ag beta- and Ag beta "-aluminas, and in Tl beta- and Tl beta "-aluminas, respectively. In these cases, there are also ordered regions in the conduction plane or slab. It is therefore suggested that an ordered structure of the conduction plane or slab should be considered in order to understand the ionic conduction in beta-alumina-type SIG.