Alpha alumina powder is produced by granulating at least one alumina starting material selected from group consisting of transition alumina and alumina compound to obtain particles and calcining the particles in a halogen-containing atmosphere which comprises a hydrogen halide gas, a halogen gas or a mixture of a halogen gas and steam and contains at least 0.1 % by volume of at least one halogen-containing gas selected from the group consisting of hydrogen halide gas and halogen gas. By granulating the alumina starting material powder in the form of particles to increase a bulk density and calcining them in the presence of halogen, alpha -alumina powder having a regulated particle size and shape and a narrow particle size distribution and containing fewer agglomerated particles is produced at a high calcining efficiency.
