Liquid ZrO₂ is one of the most important materials involved in severe accident analysis of a light-water reactor. Despite its importance, the physical properties of liquid ZrO₂ are scarcely reported. In particular, there are no experimental reports on the viscosity of liquid ZrO₂. This is mainly due to the technical difficulties involved in the measurement of thermo-physical properties of liquid ZrO₂, which has an extremely high melting point. To address this problem, an aerodynamic levitation technique was used in this study. The density of liquid ZrO₂ was calculated from its mass and volume, estimated based on the recorded image of the sample. The viscosity was measured by a droplet oscillation technique. The density and viscosity of liquid ZrO₂ at temperatures ranging from 2753 K to 3273 K, and 3170 K-3471 K, respectively, were successfully evaluated. The density of liquid ZrO₂ was found to be 4.7 g/cm ³ at its melting point of 2988 K and decreased linearly with increasing temperature, and the viscosity of liquid ZrO₂ was 13 mPa at its melting point.