In order to make a precise experiment in vitro for simulating blood flow in vivo, we have been using high concentration suspension of alginic acid gel particles in various dispersion media as a model blood. In our early study it was clarified that this model blood obeyed Casson's diagram like actual blood, and it formed aggregation at low shear rate like actual red blood cell when it was dispersed in an aqueous solution of CaCl_2. In this study we investigated an elasticity of the model blood cell by a manipulator system. As a result, the followings were clarified; the model blood cell had residual deformation when the time duration that the particle was deformed was longer than about 1 min. We measured the force that deformed the particle by pushing the particle to the tip of the beam. As a result, we got a relationship between stress and deformation of the model blood cell. Moreover we found that force relaxation occurred when the stress was inflicted on the particle in long period.