It is well known that Shuttleworth's equation shows the relation between surface stress and surface tension of the solid. But surface stress is a kind of virtual concept defined to the mathematical surface without thickness, so that the physical meanings of surface stress can not be clear. In this paper, we tried to evaluate surface stress and surface tension of homogeneous isotropic elastic body by using primitive constitutive equation derived from continuum mechanics and thermodynamics of surface. From the results, it was shown that surface stress was the stress caused in the elastic bulk which had infinity small thickness and that surface tension was the function of strain in this elastic bulk.