A new layered perovskite compound, Ag2La,2Ti3O10, was synthesized by an ion-exchange reaction of M(2)La,2Ti3O10 (M = Na,K) with a AgNO3 molten salt. The crystal structure and the ionic conductivity of the ion-exchanged compound were investigated. The ionic conductivities attributed to the interlayer silver ions were observed at high temperatures. The ionic conductivity of Ag2La2Ti3O10 was much higher than that of Na2La2Ti3O10, while the interlayer sodium ions in Na2La2Ti3O10 and silver ions in Ag2La2Ti3O10 have almost the same rock-salt type coordination. The higher conductivity of Ag2La2Ti3O10 is probably due to the higher polarizability of silver ions.