Temperature dependences of the Ag-109 chemical shift and the spin-lattice relaxation time, T-1, of Ag-109, Ag-107, and Nb-93 NMR have been measured in the room-temperature phase of Ag7NbS6 and related compounds. The Ag-109 chemical shift is about 1300 ppm and is much larger than those of other silver compounds. The Ag-109 and Ag-107 line widths are about 200 Hz, and these indicate that the motional narrowing of silver ions has been completed in this phase. T-1 of all nuclei increases with increasing temperature. The relaxational process is explainable by the fluctuations of scalar coupling between silver nuclei, because the T-1 of Ag-109 does not show any magnetic field dependence. The temperature dependences of T-1 of the mobile Ag-109 and Ag-107 are weaker than that of T-1 of the immobile Nb-93 as well found in the case of Ag9GaSe6. Though Ag7NbS6 and related compounds show a high ionic conductivity of 0.1-1 S m(-1), high affinity between the silver and chalcogenides and correlation among silver ions are suggested by the large chemical shift and by the scalar coupling, respectively.