A production method comprising the steps of: spraying an aluminum hydroxide powder having a specific surface area measured by a nitrogen adsorption method of 0.3 m2/g or more and 3 m2/g or less; a ratio of an average particle diameter D50, which is a particle diameter at which 50% by weight of particles from the finest particle side are accumulated in a particle diameter distribution measured by a laser diffraction scattering method, to a sphere conversion particle diameter Dbet calculated from a specific surface area, of 10 or less; and the average particle diameter D50 of 2 μm or more and 100 μm or less, into flames, and then collecting it in the form of a powder to give a spherical alumina powder having a small specific surface area and a low uranium content, and capable of providing high thermal conductivity to resin compositions.