The techniques of scanning force microscopy have been successfully used to investigate phase-separated polymer surfaces on a nanometer scale and been proved to be of great advantage in surface characterization studies of polymers. We observed two kinds of phase-separated surfaces of polystyrene (PS)-polyethylene oxide (PEG) blend film and injection molded crystalline engineering polymer (acetal resin)-elastomer blend plate. In the local mechanical property measurement of the PS-PEO samples, PEO domains were found to be softer and show higher friction force than PS domains with the lateral resolution of less than 100 nm. The results agree qualitatively with those of the bulk. In the local friction measurement of the acetal resin-elastomer blend plate, the surface showed stripe structures 100-300 nm wide : the lower friction region corresponds to acetal resin and the higher one to elastomer. However, in the local elasticity measurement, the difference between the two could not be detected presumably due to the subsurface effect.