A method for producing an alumina particle material according to the present disclosure includes a raw particle material preparation step of preparing a raw particle material containing alumina as a main component, a heating step of preparing a dried raw particle material by maintaining the raw particle material at 100 C. or higher for 5 minutes or more, and a surface treatment step of treating the dried raw particle material subjected to the heating step and having less moisture adsorbed on a surface thereof than that before the heating step, using a surface treatment agent, to mask at least a portion of OH groups present on the surface. Alumina constituting the alumina particle material has OH groups on a surface thereof. Since a large number of water molecules are adsorbed onto the OH groups, the adsorbed moisture is removed through the heating step.

A method for producing an alumina particle material according to the present disclosure includes a raw particle material preparation step of preparing a raw particle material containing alumina as a main component, a heating step of preparing a dried raw particle material by maintaining the raw particle material at 100 C. or higher for 5 minutes or more, and a surface treatment step of treating the dried raw particle material subjected to the heating step and having less moisture adsorbed on a surface thereof than that before the heating step, using a surface treatment agent, to mask at least a portion of OH groups present on the surface. Alumina constituting the alumina particle material has OH groups on a surface thereof. Since a large number of water molecules are adsorbed onto the OH groups, the adsorbed moisture is removed through the heating step.

An alumina powder satisfying the following expressions is provided: (Expression 1) 0.7T.sub.XT.sub.A1.3T.sub.X; (Expression 2) 0.7T.sub.XT.sub.B1.3T.sub.X; and (Expression 3) 0.7T.sub.XT.sub.C1.3T.sub.X, where T.sub.X represents a mean value of a peak height T.sub.A of a peak A in a particle size distribution of 0.3 m or more to less than 1.2 m, a peak height T.sub.B of a peak B in a particle size distribution of 0.7 m or more to less than 3 m, and a peak height T.sub.C of a peak C in a particle size distribution of 3 m or more to less than 20 m.

An alumina powder satisfying the following expressions is provided: (Expression 1) 0.7T.sub.XT.sub.A1.3T.sub.X; (Expression 2) 0.7T.sub.XT.sub.B1.3T.sub.X; and (Expression 3) 0.7T.sub.XT.sub.C1.3T.sub.X, where T.sub.X represents a mean value of a peak height T.sub.A of a peak A in a particle size distribution of 0.3 m or more to less than 1.2 m, a peak height T.sub.B of a peak B in a particle size distribution of 0.7 m or more to less than 3 m, and a peak height T.sub.C of a peak C in a particle size distribution of 3 m or more to less than 20 m.