For a reduction of period of piston development, it is very important to estimate the piston defects such as slap-noise and -vibration and skirt seizure induced by piston secondary movement and the difference of thermal expansion between piston and cylinder in engine running condition at the desktop stage. This paper describes the numerical simulation for prediction of the three dimensional skirt contact pressure and deformation in consideration of piston secondary motion. In this analysis, the iterference of piston skirt and cylinder was calculated by the geometrical consideration and reaction forces from cylinder was computed using stiffness matrix obtained in the experimental study. The validity of the results was verified by the comparison of the experimental results reported in the previous paper. After TDC firing, thrust side of the skirt was highly deformed by the piston slap.