An R-T-B based sintered magnet according to the present invention has a composition comprising: 12 at % to 15 at % of a rare-earth element R; 5.0 at % to 8.0 at % of boron B; 0.1 at % to at % of Al; 0.02 at % to less than 0.2 at % of Mn; and a transition metal T as the balance. The rare-earth element R is at least one element selected from the rare-earth elements, including Y (yttrium), and includes at least one of Nd and Pr. The transition element T includes Fe as its main element.