A high zirconia electrically fused cast refractory of high electric resistance having long time durability, less suffering from cracking during production and upon temperature rising, excellent in productivity, less forming zircon crystals even upon heating the refractory in itself and when the refractory is in contact with molten glass, generating less cracks even when undergoing heat cycles during operation of a glass melting furnace is provided. A high zirconia electrically fused cast refractory has, as chemical components, 85 to 95% by weight of ZrO2, 0.1 to less than 0.8% by weight of Al2O3, 3.5 to 10.0% by weight of SiO2, less than 0.05% by weight of Na2O and K2O in total, 0.1 to 1.5% by weight of B2O3, 0.1% by weight or less of MgO, 0.01 to 0.2% by weight of CaO, in the case where any one of BaO and SrO is contained, from 0.05 to 3.0% by weight of BaO or 0.01 to 3.0% by weight of SrO, or in the case where both of them are contained, 0.01% by weight or more of SrO and from 0.01% to 3.0% by weight in total of SrO and BaO, 0.1 to 0.7% by weight of SnO2, 0.3% by weight or less of Fe2O3 and TiO2 in total, less than 0.01% by weight of P2O5, and less than 0.01% by weight of CuO.