For wax layer of wax-polished painted smooth surfaces, specular reflectance curves of p-polarized monochromatic light incident at angles near Brewster's angle are obtained by measurement, the electric vector of the light being parallel to the plane of incidence. The layer thickness, found graphically from minimum of the curve by referring to data obtained by calculating the formula of film reflection, is different for different wavelengths (641, 548 and 435mμ) of used light unless, the surface of substrate is optically flat. The informations on varied states of wax spread on the surface are obtained from the characteristics of the specular reflectance curves. The dependence of the layer thickness on wavelength is interpreted by the surface irregularities. The layer thickness is found less than 800Å.