In a stiffness estimation of living body, an internal structure under the skin influences the measured results. Because a different stiffness of body caused by bones and muscles is obtained. In this paper, by using a measurement system of mechanical impedance, the relations between a viscoelasticity and a distance from the surface of silicone-gel model is calculated. This relation is applied to silicone-gel tumor model and a shape and a viscoelasticity of semi-sphere silicone-gel tumous are estimated. The obtained results are expressed as a reconstructed 3-D image of shape / viscoelasticity. The revised curve-fitting of mechanical impedance and the cancellation of peripheral vibration influence are proposed in order to increase an estimation acccuracy.