Alumina sintered body, the abrasive grains, and the grinding wheel

Provided are an alumina sintered compact containing a titanium compound and an iron compound, wherein the total amount of the TiO 2 -equivalent content of the titanium compound, the Fe 2 O 3 -equivalent content of the iron compound and the alumina content is at least 98% by mass, the total amount of the TiO 2 -equivalent content of the titanium compound and the Fe 2 O 3 -equivalent content of the iron compound is from 5 to 13% by mass, and the ratio by mass of the TiO 2 -equivalent content of the titanium compound to the Fe 2 O 3 -equivalent content of the iron compound (TiO 2 /Fe 2 O 3 ) is from 0.85/1.15 to 1.15/0.85; and an abrasive grain and a grain stone using the alumina sintered compact.