Surface conductance is measured for polycrystalline 8 mol% Y2O3-ZrO2 by the dc 3-probe method. The dc 4-probe method is used to measure surface conductance without electrode resistance. Apparent thermal activation energies of surface and electrode conductance are almost the same and the value is about 1 eV. This differs with bulk conductance in that surface conductance has P(O2) dependence. The thermal activation energy of surface conductance also has P(O2) dependence.