The life of a rolling bearing is predominantly determined by the contact stress between the rolling elements (ball and roller) and the raceway of inner and outer rings. The contact stress is calculated by assuming Hertzian stress distribution. The maximum Hertzian contact stress Pmax usually ranges from 2000 to 3000 MPa in actual service of rolling bearings. These figures are rather large compared to the compressive yield strength of hardened bearing steel (σys = 2000 MPa). Therefore plastic deformation sometimes occurs under the raceway, creating residual compressive stress. Several investigators have so far reported about the residual stress due to rolling contact. There were, however, few who referred to the residual stress in used bearings and application of residual stress measurement to failure analysis.