Abstract: Piezoresistance effect of the In_xGa_{1 – x}As nanowires was studied by scanning probe microscopy. The effect was investigated by measuring of the I–V curves with simultaneous bending of the nanowire by the probe. A modulation of the conductivity of In_0.85Ga_0.15As NWs induced by a mechanical stress exceeding three orders of magnitude was observed. For the explanation a model based on the surface states is presented. Such an observation opens new ways for the design of electromechanical switches with record parameters.