This paper describes the establishment of a new method for predicting piston skirt scuffing in the internal combustion engine of a passenger car. The authors previously constructed and reported a method that uses 3D piston motion simulation to predict piston slap noise and piston skirt friction. However, that simulation did not have a clear index for evaluation of scuffing that involves piston skirt erosion, and it impressed shortage of the predictive accuracy of a scuffing. Therefore, the authors derived a new evaluation index for piston skirt scuffing by actually operating an internal combustion engine using multiple types of pistons to reproduce the conditions under which scuffing occurs, and comparing with the results of calculating the same conditions by piston motion simulation. In addition, it was clarified that in these calculations it is important to accurately predict the behavior of the oil film between the piston skirt and cylinder liner, and that this requires understanding of the piston skirt surface property parameters, so a method of applying these parameters was indicated. Furthermore, the newly obtained evaluation index was confirmed to be effective even for pistons of different shapes, which validated the general versatility of this prediction method. Use of this prediction method made it possible to clearly distinguish and predict wear and scuffing of the piston skirt.