Self-healing breakdowns of anodic Y2O3 films with the thickness of 500 to 2000 have been measured. The measurements reveal that the breakdown is a single-hole type and that the breakdown field, which is closely correlated to the anodizing field, is independent of the Y2O3 thickness. An ionic motion is considered to the effective in initiating the breakdown which forms a conducting channel through the Y2O3 film. The energy of the breakdown spot formation is calculated assuming the thermochemical evaporation process of the substances. It agrees well with the discharged energy of the specimen capacitor at the breakdown.