A method for producing an R-T-B based sintered magnet comprising: a step of preparing an R-T-B based sintered magnet material, which is represented by the following formula: uRwBxGayCuzAlqM(100-u-w-x-y-z-q)T where R is composed of light rare-earth element(s) RL and a heavy rare-earth element(s) RH, RL is Nd and/or Pr, RH is at least one of Dy, Tb, Gd and Ho, T is a transition metal element and includes Fe, M is Nb and/or Zr, and u, w, x, y, z, q, and 100-u-w-x-y-z-q are expressed in terms of % by mass; the RH accounts for 5% by mass or less of the R-T-B based sintered magnet, the following inequality expressions to being satisfied: 0.20 ≤ x ≤ 0.70 0.07 ≤ y ≤ 0.2 0.05 ≤ z ≤ 0.5 0 ≤ q ≤ 0.1 v = u - (6α + 10β + 8γ), where the amount of oxygen (% by mass) of the R-T-B based sintered magnet is α, the amount of nitrogen (% by mass) is β, and the amount of carbon (% by mass) is γ; when 0.40 ≤ x ≤ 0.70, v and w satisfy the following inequality expressions and: 50 w − 18.5 ≤ v ≤ 50 w − 14 − 12.5 w + 38.75 ≤ v ≤ − 62.5 w + 86.125 and, when 0.20 ≤ x < 0.40, v and w satisfy the following inequality expressions and, and x satisfies the following inequality expression: 50 w − 18.5 ≤ v ≤ 50 w − 15.5 − 12.5 w + 39.125 ≤ v ≤ − 62.5 w + 86.125 − 62.5 w + v − 81.625 / 15 + 0.5 ≤ x ≤ − 62.5 w + v − 81.625 / 15 + 0.8 a high-temperature heat treatment step of heating the R-T-B based sintered magnet material to a temperature of 730°C or higher and 1,020°C or lower, and then cooling to 300°C at a cooling rate of 20°C/min; and a low-temperature heat treatment step of heating the R-T-B based sintered magnet material, after the high-temperature heat treatment step, to a temperature of 440°C or higher and 550°C or lower. a step of preparing an R-T-B based sintered magnet material, which is represented by the following formula: uRwBxGayCuzAlqM(100-u-w-x-y-z-q)T where R is composed of light rare-earth element(s) RL and a heavy rare-earth element(s) RH, RL is Nd and/or Pr, RH is at least one of Dy, Tb, Gd and Ho, T is a transition metal element and includes Fe, M is Nb and/or Zr, and u, w, x, y, z, q, and 100-u-w-x-y-z-q are expressed in terms of % by mass; the RH accounts for 5% by mass or less of the R-T-B based sintered magnet, the following inequality expressions to being satisfied: 0.20 ≤ x ≤ 0.70 0.07 ≤ y ≤ 0.2 0.05 ≤ z ≤ 0.5 0 ≤ q ≤ 0.1 v = u - (6α + 10β + 8γ), where the amount of oxygen (% by mass) of the R-T-B based sintered magnet is α, the amount of nitrogen (% by mass) is β, and the amount of carbon (% by mass) is γ; when 0.40 ≤ x ≤ 0.70, v and w satisfy the following inequality expressions and: 50 w − 18.5 ≤ v ≤ 50 w − 14 − 12.5 w + 38.75 ≤ v ≤ − 62.5 w + 86.125 and, when 0.20 ≤ x < 0.40, v and w satisfy the following inequality expressions and, and x satisfies the following inequality expression: 50 w − 18.5 ≤ v ≤ 50 w − 15.5 − 12.5 w + 39.125 ≤ v ≤ − 62.5 w + 86.125 − 62.5 w + v − 81.625 / 15 + 0.5 ≤ x ≤ − 62.5 w + v − 81.625 / 15 + 0.8 a high-temperature heat treatment step of heating the R-T-B based sintered magnet material to a temperature of 730°C or higher and 1,020°C or lower, and then cooling to 300°C at a cooling rate of 20°C/min; and a low-temperature heat treatment step of heating the R-T-B based sintered magnet material, after the high-temperature heat treatment step, to a temperature of 440°C or higher and 550°C or lower.