The density of metastable excited Ar atoms in the vicinity of a surface in a barrier discharge was measured by the laser-induced evanescent-mode fluorescence technique. The temporal and spatial distributions of excited atoms in the barrier discharge were also measured by conventional spontaneous emission and laser absorption methods in order to clarify the behavior of the excited species. It was also found that a technique using an evanescent wave spectroscopy makes it possible to measure the density distribution of the atoms in the vicinity of a surface.