To provide (1) a method for producing a scandium oxide powder excellent in sinterability by an industrially practicable technique and (2) a method for producing a scandium oxide sintered compact exhibiting good transparency in the visible and infrared regions by using the scandium oxide powder.

An easily sinterable scandium oxide powder having a primary particle size of 10-300 nm is produced by calcining scandium sulfate in a temperature range of from 1,000°C to 1,300°C. Thus produced easily sinterable scandium oxide powder is used to form a molded body. The transparent scandium oxide sintered compact is produced by firing the molded body in an atmosphere wherein the sum of partial pressures of gases, such as a nitrogen gas and a gas containing an element (e.g. argon) substantially incapable of diffusing in scandium oxide, is 0.03 MPa or lower.

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