The aim of this study is to measure spatial distribution of local elasticity in living cell surfaces. A scanning probe microscope (SPM) has been developed as a powerful tool for obtaining high resolution topographic images of biological samples. The SPM can also be used to evaluate mechanical properties because its probe is physically in contact with the samples during measurement. To obtain cellular stiffness with SPM, we have developed two methods: a force modulation mode and a force mapping mode. It was revealed that spatial and temporal distributions of cellular stiffness originate in cytoskeletal distribution, mode of cellular migration, and intracellular contractile force.