The oriented structure of the exposed V=O bond of vanadium oxides on ZrO2(100) was studied by in situ polarized total-reflection fluorescence X-ray absorption near-edge structure (XANES) spectroscopy. The pre-edge peak intensity of s-polarized XANES was half the intensity of the p-polarized one. Moreover, both pre-edge peaks decreased in a similar way and eventually became zero by the reaction of V=O bonds with NH3 at 423 K, suggesting that all of the observed V=O bonds behaved as active sites. The present technique suggests that the exposed V=O bonds are oriented to a 45-degrees-direction from the normal to the ZrO2(100) surface.