The air film thickness between a foil and a drum is studied experimentally using a measuring system under condition where the Air film thickness is effect by the bending stiffness of the foil. For comparatively flexibl e foil cases, the experimental results coincide fairly well with theoretical ones obtained by applying the separ ation boundary condition. For cases with stiffer foil conditions, the tendency of the experimental results may also be explained well by the theoretical analysis, by introducing the concept of the tangency point condition as well as the infinity point condition for the film pressure generation point. The theoretical tool of Finite El ement Method is used to analyze film thickness and pressure distribution in a foil bearing for various values of foil stiffness, the calculated results agree with the experimental data, and it is concluded that the shallow shells model is useful and accurate.