Freestanding monolayers of two-dimensional particle arrays, in which fine particles are two-dimensionally self-assembled in a highly oriented manner, was prepared to examine the influence of substrate on the transmission spectra of 2D particle array; as a result, the spectrum of the freestanding 2D particle array has less noise than that of the 2D particle array on the substrate, and besides, agree with the theoretical result particularly in the near-field discussion.