Local elasticity was measured on polymers by modifying atomic force microscopy (AFM) in which the sample height was modulated and the response of the cantilever was detected. Tn a case of polystyrene (PS) on mica, there existed many circular holes in the film that were stiffer than the rest parts. The holes were identified as the substrate mica surface and the rest as PS films. In the case of a polyethyleneoxide surface on mica, a crystalline nature was observed. In addition, the surface was modified by scanning an AFM tip at large forces of 20 nN. The scanned area exhibited an increase in elasticity as well as formation of a striped structure.