In order to detect local motion of mobile silver cations in organic-inorganic mixed glasses composed of AgI and alkylammonium iodides, their electrical conductivity at radio and microwave frequencies was measured in different compositions. Although their DC conductivity shows a clear transition from insulator to superionic conductor at AgI volume fraction phi similar to 0.35, the high frequency value is continuous at the threshold. Details of frequency dependence were measured at room temperatures from DC to 10 GHz. Only a small dependence was seen in the high conducting glasses, however, the sample near the percolation threshold showed power-law dependence sigma[omega] similar to omega(n) at low frequency whose slope n similar to 0.6 and approaches to unity at high frequencies.