Contact pressure is one of the most important factors in fretting fatigue. The contact pressure distribution on loading of applied cyclic stress is markedly different from that on unloading. To elucidate the effect of contact pressure on fretting fatigue strength, the contact pressure distribution should be exactly determined. In this paper, the contact pressure distribution was calculated by using a boundary element method and monitored by an experimental method of caustics. Differences in the contact pressure distribution between the shapes of fretting bridges whose height is 10, 15, 20, and 30 mm at a constant span of 30 mm, and between two types of clamping, which are center clamping and edge clamping at the back face of the bridge, were analyzed. In order to examine the effect of the contact pressure distribution on the fretting fatigue strength, fretting fatigue tests in plane bending were carried out. The S-N properties obtained from fretting fatigue tests could be estimated analytically by equivalent stress amplitude.