Surface-enhanced Raman scattering (SERS) is a sensitive and widely used as spectroscopic technique for chemical and biological structure analysis. One of the keys to increase the sensitivity of SERS sensors is to use nanoparticles/nanostructures. Here, we report on the density effect of gold nanodisks on SERS intensity for a highly sensitive detection of chemical molecules. Various densities of gold nanodisks with a height of 30 nm on gold/glass substrate were fabricated by electron beam lithography in order to have a good uniformity and reproducibility. The evolution of the enhancement factor (EF) with nanodisk density was quantified and compared to numerical calculations. An EF as high as was measured for the nanodisk with a diameter of 110 nm and a periodicity of 150 nm which corresponds to the highest density (42.2 %).