Provided is a method for producing a wavelength conversion sintered body that emits light under irradiation of excitation light. The method for producing a wavelength conversion sintered body includes: preparing a molded body obtained by molding a mixture containing an α-SiAlON fluorescent material and aluminum oxide particles and having a content of Ga of 15 ppm by mass or less; and primary calcining the molded body at a temperature in a range of 1,370° C. or more and 1,600° C. or less to obtain a first sintered body.