Zirconia containing 2.85 mol % Y2O3 and 1.42 mol % HfO2 was repeatedly rubbed in one direction without lubricant at room temperature. Transmission electron diffraction (TEM diffraction) taken from the above specimen revealed a structure created as the sum of the contributions of compounds of the composing elements. Further, this also showed halo rings that suggest amorphous zirconium formation. These transformations act as mechanisms of plastic deformation during rubbing.