Raw material for zirconia/mullite refractory and plate brick

Provided is a zirconia-mullite refractory raw material which is less likely to undergo alternation and microstructural degradation under high-temperature conditions, and low in thermal expansion rate, so as to have thermal shock resistance and corrosion resistance. The zirconia-mullite refractory raw material comprises crystalline zirconia and mullite as primary components, with the remainder being corundum and/or a matrix glass, wherein the crystalline zirconia includes a eutectic zirconia crystal having a grain size of 1.0 μm or less, and has a maximum grain size of 30 μm or less, and the matrix glass is contained in an amount of 5 mass % or less. The zirconia-mullite refractory raw material has a chemical composition comprising 30 to 55 mass % of ZrO2, 30 to 55 mass % of Al2O3 and 10 to 25 mass % of SiO2, wherein each of the chemical components falls within a primary phase region of ZrO2 in an Al2O3-ZrO2-SiO2 system phase diagram.