Provided is a sintered R-T-B based magnet having high Br and high HcJ. A sintered R-T-B based magnet containing: R: 26.8 mass % or more and 31.5 mass % or less (R is a rare earth element, and necessarily contains Pr); M: 0.05 mass % or more and 2.00 mass % or less (M is at least one selected from the group consisting of Ga, Cu, Zn, Al, and Si, and necessarily contains Cu); B: 0.84 mass % or more and 0.94 mass % or less; and T: 61.5 mass % or more (T is Fe and Co, and 90% or more of T is Fe in mass ratio), and having an internal structure, wherein the internal structure includes: crystal grains; a first phase between adjacent two crystal grains; and a second phase with Cu and Pr concentrations higher than those of the first phase between the first phase and one or each of the two crystal grains and, wherein the second phase contains Pr of 20 mass % or more 65 mass % or less.