Efforts to elucidate the rolling contact fatigue of rails are being vigorously implemented in Japan and overseas. The X-ray diffraction line profile analysis is expected as a method for quantitatively evaluating the strain of a material, but there are few examples of its application to practical materials. In order to establish this method as a useful method for quantifying the effect of rolling contact of rails, it is necessary to experimentally clarify basic matters such as the correlation between the analysis result and the degree of rolling contact fatigue. In this study, a twin-disc test was conducted using a rail steel test piece. The purpose of the twin-disc test is to prepare test pieces with different degrees of rolling contact fatigue. The degree of rolling contact fatigue of each test piece was evaluated by the tendency of crack generation and the depth of the plastic flow by observing the metallographic structure. Furthermore, the X-ray diffraction line profile analysis was performed on each test piece to understand the correlation between the results.