The effect of applying a DC voltage on the wettability of zirconia by liquid copper and the possibility of utilizing this technique to join copper to zirconia were investigated. A forced migration of oxygen in the stabilized zirconia, an oxygen ionic conductive material, resulted when a DC voltage was applied to the interface between copper and zirconia. It has been shown that the forced migration of oxygen from or to the interface by applying a DC voltage resulted in the deoxidation or oxidation reaction at the interface and the wettability of zirconia was affected. Furthermore, it was confirmed that this technique of applying a DC voltage was applicable to the joining of solid copper-zirconia.