PROBLEM TO BE SOLVED: To provide a method for producing fine particles of a rare earth oxide.SOLUTION: The method for producing fine particles of a rare earth oxide is capable of producing fine particles of a rare earth oxide by comprising: a mixing step of mixing a rare earth compound containing at least one rare earth element selected from the group consisting of yttrium, neodymium, dysprosium, and holmium with a carboxylic acid; a heating step of mixing the mixed liquid obtained in the mixing step with a primary amine and heating the mixture to obtain a rare earth oxide having an average particle diameter exceeding 10 nm and an average thickness of 5 nm or less; a separation step of separating the rare earth oxide; a firing step of firing the rare earth oxide separated in the separation step at 550-1000°C; and a crushing step of crushing the rare earth oxide fired in the firing step.
