PURPOSE: To obtain an oxide of rare earth element having approximately spherical shape not collapsing by burning by heat-treating a oxalate of rare earth element in a high-boiling alcoholic solvent in a specific temperature range.

CONSTITUTION: In a method of obtaining an oxide of rare earth element by burning an oxalate of rare earth element, the oxalate is treated as follows. Namely, an oxalate of rare earth element is filtered, washed with water, sufficiently dried, separated from free water and heat-treated in a high-boiling alcoholic solvent at 120-200°C for 1-5 hours. Then the heat-treated material is filtered and burnt. Glycerol is preferably used as the high-boiling alcoholic solvent. When the heat-treating condition is <120°C, granule shape change is insufficient and when exceeds 200°C, the operation is difficult. When heating time is <1 hour, granule shape change is insufficient and when exceeds 5 hours, there is fear of evaporation and change of quality of the solvent.