In this chapter, the effect of the hydrated viscoelastic property of polymer surfaces on the protein adsorption and adhesion behavior of cells is introduced. Various factors governing cellular responses to artificial materials have been studied in recent decades. Even though it has been clarified that the amount of protein adsorption, adhering density or proliferation rate of cells is strongly dependent on the traditional physicochemical factor, i.e., surface free energy, the critical factors that dominate the adsorption states of protein or adhering morphology of cells are yet to be studied extensively. The characteristic adsorption behavior of proteins and the adhesion behavior of cells are discussed in terms of the hydrated viscoelastic factor of dynamic supra-molecular surfaces.