An aluminum oxide sintered product including a layer phase containing a rare-earth element and fluorine among grains of aluminum oxide serving as a main component, or a phase containing a rare-earth element and fluorine along edges of grains of aluminum oxide serving as a main component. The product includes a phase containing a rare-earth element and a fluorine element among grains of aluminum oxide, the phase not being in the form of localized dots but in the form of line segments, when viewed in an SEM image. The product can be readily adjusted to have a volume resistivity in the range of 1×1013 to 1×1016 Ω·cm, the volume resistivity being calculated from a current value after the lapse of 1 minute from the application of a voltage of 2 kV/mm to the aluminum oxide sintered product at room temperature.