Recently, X-ray Dark-Field Imaging utilizing a Laue geometry analyzer has been proposed. The optimum imaging condition for depicting articular cartilage by X-ray Dark-Field Imaging utilizing X-ray of 36 keV from synchrotron radiation was researched by observing the edge contrast of acrylic sphere as a simple case. It was observed that a difference in image contrast appeared at the edges of right and left side of acrylic sphere. This must be an undesirable contrast at thin articular cartilage on the head of phalanx. In order to avoid this contrast overlapping with articular cartilage, which might lead to a wrong diagnosis, we suggested that a bone head on which articular cartilage locates should be directed to the same sense as the scattering vector of the Laue case analyzer crystal. Under this condition minute defects of articular cartilage and an irregular surface of subchondral bone beneath its defect areas were successfully detected. Utilized under the optimum imaging condition, X-ray Dark- Field Imaging will be a powerful tool for a diagnosis of arthropathy since minute change of articular cartilage and/or irregularities of subchondral bone may be the features of its early stage, which may create a new strategy of diagnosis.