Surface enhanced Raman scattering (SEES) effect of benzoic acid adsorbed at silver electrode surface is investigated, and SEES spectra of Ag/0.02 M C6H5COOH+0.1 Na2SO4 have been recorded. Enhancement factor is estimated at 1.1*.106. The pretreating of electrode and the pH of solution which affect enhancement are discussed. SEES spectra of benzoic acid recorded from various SEES active systems are compared. Experimental results can be qualitatively explained by surface active site and surface carbon model.