In order to investigate the time-dependent change of activation energy for electrical conduction of Y2O3-stabilized ZrO2 containing 8 mol% Y2O3, the electrical conductance of a sintered sample was measured in the range of 1090-1110 degrees C over a period of 114 days. The activation energy increased with the time-dependent decrease of conductance. The stationary activation energy may be about 1.10 eV at 1100 degrees C.