An R-(Fe,Co)-B base sintered magnet of a composition consisting essentially of; 12 to 17 at% of R which is at least two of yttrium and rare earth elements and essentially contains Nd and Pr, 0.1 to 3 at% of M 1 which is at least one element selected from the group consisting of Si, Al, Mn, Ni, Cu, Zn, Ga, Ge, Pd, Ag, Cd, In, Sn, Sb, Pt, Au, Hg, Pb, and Bi, 0.05 to 0.5 at% of M 2 which is at least one element selected from the group consisting of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W, 4.8+2×m to 5.9+2×m at% of B wherein m is at% of M 2, up to 10 at% of Co, up to 0.5 at% of carbon, up to 1.5 at% of oxygen, up to 0.5 at% of nitrogen, and the balance of Fe, containing R 2 (Fe,Co) 14 B intermetallic compound as a main phase, and having a coercivity of at least 796 kA/m (10 kOe) at room temperature, wherein the magnet contains an M 2 boride phase at a grain boundary triple junction, but not R 1.1 Fe 4 B 4 compound phase, has a core/shell structure that the main phase is covered with a grain boundary phase, the grain boundary phase being composed of a nanocrystalline or an amorphous and nanocrystalline R'-(Fe,Co)-M 1 ' phase consisting essentially of; 25 to 35 at% of R' which consists of at least 5 at% of Pr and the balance of Nd and at least one of yttrium and rare earth elements, and contents of Pr in R' is higher than that of R 2 (Fe,Co) 14 B intermetallic compound as a main phase, 2 to 8 at% of M 1 ' wherein M 1 ' is at least one element selected from the group consisting of Si, Al, Mn, Ni, Cu, Zn, Ga, Ge, Pd, Ag, Cd, In, Sn, Sb, Pt, Au, Hg, Pb, and Bi, up to 8 at% of Co, and the balance of Fe, or the R'-(Fe,Co)-M 1 ' phase and an amorphous and/or nanocrystalline R'-M 1 '' phase containing at least 50 at% of R' wherein M 1 '' is at least one element selected from the group consisting of Si, Al, Mn, Ni, Cu, Zn, Ga, Ge, Pd, Ag, Cd, In, Sn, Sb, Pt, Au, Hg, Pb, and Bi, a coverage of the main phase with the R'-(Fe,Co)-M 1 ' phase is at least 50% by volume, and the width of the grain boundary phase between two main phase grains is at least 50 nm on average. 12 to 17 at% of R which is at least two of yttrium and rare earth elements and essentially contains Nd and Pr, 0.1 to 3 at% of M 1 which is at least one element selected from the group consisting of Si, Al, Mn, Ni, Cu, Zn, Ga, Ge, Pd, Ag, Cd, In, Sn, Sb, Pt, Au, Hg, Pb, and Bi, 0.05 to 0.5 at% of M 2 which is at least one element selected from the group consisting of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W, 4.8+2×m to 5.9+2×m at% of B wherein m is at% of M 2, up to 10 at% of Co, up to 0.5 at% of carbon, up to 1.5 at% of oxygen, up to 0.5 at% of nitrogen, and the balance of Fe, containing R 2 (Fe,Co) 14 B intermetallic compound as a main phase, and having a coercivity of at least 796 kA/m (10 kOe) at room temperature, wherein the magnet contains an M 2 boride phase at a grain boundary triple junction, but not R 1.1 Fe 4 B 4 compound phase, has a core/shell structure that the main phase is covered with a grain boundary phase, the grain boundary phase being composed of a nanocrystalline or an amorphous and nanocrystalline R'-(Fe,Co)-M 1 ' phase consisting essentially of; 25 to 35 at% of R' which consists of at least 5 at% of Pr and the balance of Nd and at least one of yttrium and rare earth elements, and contents of Pr in R' is higher than that of R 2 (Fe,Co) 14 B intermetallic compound as a main phase, 2 to 8 at% of M 1 ' wherein M 1 ' is at least one element selected from the group consisting of Si, Al, Mn, Ni, Cu, Zn, Ga, Ge, Pd, Ag, Cd, In, Sn, Sb, Pt, Au, Hg, Pb, and Bi, up to 8 at% of Co, and the balance of Fe, or the R'-(Fe,Co)-M 1 ' phase and an amorphous and/or nanocrystalline R'-M 1 '' phase containing at least 50 at% of R' wherein M 1 '' is at least one element selected from the group consisting of Si, Al, Mn, Ni, Cu, Zn, Ga, Ge, Pd, Ag, Cd, In, Sn, Sb, Pt, Au, Hg, Pb, and Bi, a coverage of the main phase with the R'-(Fe,Co)-M 1 ' phase is at least 50% by volume, and the width of the grain boundary phase between two main phase grains is at least 50 nm on average.