The nanometer-scale wearing property of the fatigued polycarbonate (PC) surface was studied using an atomic force microscope (AFM). The PC sample was fatigued mechanically by applying cyclic compressive strain using a piezoactuator device that could be fixed on the sample stage of the AFM. The direction of the compressive strain in the thin sample was parallel to the surface observed with: the AFM. The surface morphology changed and became rougher under the fatigue process. Before the PC sample was fatigued, the formation of a periodic bundle structure was,observed at the scan-scratched area. However, after the repetitive strain was applied to the PC sample, the fatigued surface was worn down easily by scan scratching without the formation of bundles. The elasticity of the PC surface was observed using ultrasonic force microscopy. After the fatigue progress, the elasticity of the PC surface decreased entirely due to many microcracks generated by applying repetitive strain.:However, the:elasticity of the scratched worn-down area was at most the same as that of an unworn surface.