As the reference data for the contact deformation in a ball bearing, the contact deformation and its elastic recovery on the surface where comparatively small imprint occurs were investigated. For the above experiment the air-micrometer was applied to measure the amount of deformation. The experimental results obtained are as follows : The magnitude of contact deformation is approximated by Hertz's equation within comparatively low mean contact pressure and its elastic recovery is also given in the same form as Hertz's equation, tut the load exponent is rather small. Liquid lubricant gives little effect to contact deformation and in the case of solid lubricant the contact deformation increases rapidly within the range of mean contact pressure 130 kg/mm2 and after that it reaches the state similar to that or liquid lubricated surface. The maximum value of deformation and the depth of imprint are not so much effected by repetitive loading at the same position. An equation of rolling frictional resistance is reduced by deformation work obtained from the deformation and elastic-recovery curves.