Attenuated total reflection (ATR) properties have been investigated as a function of incident angles of visible laser beams for LB ultrathin films of arachidic cadmium salt on Ag and Al thin films. The ATR properties are measured for the LB ultrathin films with different numbers of the monolayers. The resonance angles for both the LB films on Ag and Al films strongly depend upon the number of the monolayers. The calculated ATR curves fit the experimental ones, assuming that the complex dielectric constants are isotropic and constant for all LB films. The thicknesses of the LB monolayers are decided from the theoretical curves. The result shows that the deposition of the LB films on Al films is better than the one on Ag films. The ATR measurement has not been reported for LB films on Al films until now. It is thought that the ATR measurement for LB films on Al films is very useful because most LB films are easily deposited on Al thin films.