An aluminum oxide sintered body contains aluminum oxide in an amount of not less than 99% by weight and at least one selected from magnesium oxide, calcium oxide and silicon oxide, and contains phosphorus of not more than 0.0025 parts by weight to 100 parts by weight of the aluminum oxide sintered body. This avoids that phosphorous exerts adverse effect on the sintering properties of an aluminum oxide sintered body, especially the sintering properties of a large aluminum oxide sintered body, causing the sintered body to lack uniformity between the sintered body inner portions and outer portions. Therefore, this aluminum oxide sintered body is suitably used in semiconductor manufacturing apparatus members or liquid crystal manufacturing apparatus members.