PURPOSE: To minimize the degree of volume shrinkage and to efficiently produce a calcined body with reduced residual stress by mixing rare-earth oxide fine powder B which has been calcined at high temp. into the hydrate obtained by adding water to rare-earth oxide fine powder A to form a slurry, forming the mixture, drying and sintering the formed product.

CONSTITUTION: Water is added to the rare-earth oxide powder A having ≤1μm average grain diameter to obtain the hydrate, and 75 pts.wt. of the rare-earth oxide powder B which has been sintered at high temp. and crushed is added to 100 pts.wt. of the powder A to form a slurry (Y2O3, Dy2O3 and Er2O3 are appropriately used for the powders A and B). The slurry is formed, and the formed product is dried and sintered to produce the rare-earth oxide sintered body. Consequently, the degree of volume shrinkage of the rare-earth oxide powder when sintered is minimized, and the sintered body is obtained in good yield.