R a-T a-B based sintered magnet

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[Problem] To provide a method for producing an R-T-B sintered magnet, having an excellent HcJ temperature coefficient, a minimal drop in HcJ at high temperatures, and with which it is possible to obtain a high HcJ. [Solution] A method for producing an R-T-B sintered magnet, comprising : a step in which an R-T-B sintered magnet material containing 29.5-35.0 mass% R, 0.80-0.90 mass% B, 0.1-0.8 mass% Ga, 0-2 mass% M, with the remainder being made up of T and unavoidable impurities is prepared; an RH diffusion step in which an RH diffusion source containing the heavy rare earth element RH and the R-T-B sintered magnet material are heated, and the heavy rare earth element RH is diffused in the R-T-B sintered magnet material from the RH diffusion source; a high-temperature heat-treatment step in which the R-T-B sintered magnet which has been subjected to the RH diffusion step is heated to a high temperature of 730-1020°C, and subsequently cooled to 300°C at a rate of at least 5°C/minute; and a low-temperature heat-treatment step in which the R-T-B sintered magnet having undergone the high-temperature heat-treatment step is heated to a temperature of 440-550°C.