We have developed a cell palpation system to investigate cell stiffness from the reaction force generated on a particle that is fixed on a cell. In this method, a particle is used as a probe, and is manipulated towards a cell using optical tweezers. Using this method, we can obtain information of local stiffness of a cell. We investigate focal adhesion formation of a cell probed by a particle and we report different particle coating utilized for attaching certain protein in cell membrane. Also we discuss the effects of endocytosis.