In an atomic force microscopic image of the main-chain- and the side-chain-type polyimide surfaces, we have observed a variation of the surface morphology to use the rubbing depths and the rubbing times. On the rubbed polyimide surface, the polymer clusters are aligned in long chains along the rubbing direction. The topology of the polyimide surface is weakly changed at a lower rubbing depth, but it is greatly changed at a deeper rubbing depth. Once the polished string structure is obtained, no considerable changes in the surface topography of the polyimide are visible, although rubbing times are increased from 1 to 8 at constant rubbing depths (0.3 mm). The rubbed polyimide films show optical phase retardation, which was steeply increased with increasing rubbing depth; but it was increased very little with increasing rubbing times. (C) 2000 John Wiley & Sons, Inc.