NDT(Non-Destructive Testing) is useful for the defect detection of rolling stock because it can be used to detect defects in many invisible parts. In rolling stock one of the components vulnerable to damage is the axle. Fatigue cracks are initiated in press-fitted parts such as the wheel and brake disk seats of the axle. Those parts suffer from fretting fatigue damage. A precise and reliable NDT technique is necessary to detect cracks in the axle. But conventional induced current potential drop methods (ICPD) have some difficulties to detect such cracks in press-fitted parts of axles. In this study, we have introduced an induced current focusing potential drop method (ICFPD), a new concept that can be applied to the press-fitted parts of the axle. And we have measured electromagnetic properties of the wheelsets and performed finite element analysis for wheelsets with defects. Results suggest that the method is very powerful and effective to detect defects.