Raman and infrared spectra of a layered structure compound AgTaS3 were measured for the polycrystalline samples. The wavenumbers of the Raman or infrared active modes were calculated using Keating-type force constants, and the observed spectra have been assigned peaks due to the translational lattice modes of the silver atoms between Ta-S slabs were observed in the low wavenumber region below 100 cm(-1) of the infrared spectra. On the basis of the eigenvectors obtained, the relative infrared intensities of the individual infrared active modes and the relative Raman intensities of the individual Raman active modes were calculated using the empirical parameters. The results are in approximate agreement with the observed data.