A process for producing alumina particles, comprising vaporizing aluminum chloride to form an aluminum chloride vaporized gas, which optionally contains an inert gas, and oxidizing the vaporized aluminum chloride with an oxidizing gas to produce alumina particles, wherein the aluminum chloride vaporized gas and the oxidizing gas are introduced into a reactor each at an ejecting flow velocity of about 10 m/sec or more, the ratio of the flow velocity of oxidizing gas to the flow velocity of the aluminum chloride vaporized gas is approximately from 0.2 to less than 10, and the amount of oxidizing gas is about 1 or more times the amount of oxidizing gas necessary for stoichiometrically oxidizing aluminum chloride.