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SOLUTION : An R-Fe-B based sintered magnet includes M2 boride phases and no R1.1Fe4B4 compound phase at triple points of grain boundaries, and has main phases of (R, HR)2(Fe, (Co))14B(R is a rare earth element, and HR is Dy, Tb or Ho). The main phases are coated with HR-rich layer of 0.01-1.0 μm in thickness. The R-Fe-B based sintered magnet has a core-shell structure in which the main phases are coated by : (R, HR)-Fe(Co)-M1 phases of amorphous and/or micro crystalline of 10 nm or smaller; or grain boundary phases including the (R, HR)-Fe(Co)-M1 phases, and (R, HR)-M1 phases of crystalline, or micro crystalline of 10 nm or smaller and amorphous with R accounting for 50 atom% or more. The superficial area coverage concerning the main phases each having an HR-rich layer of (R, HR)-Fe(Co)-M1 phase is 50% or more. The phase width of the grain boundary phase located between two grains of the main phases is 10 nm or larger, which is 50 nm or larger on average. EFFECT : A magnet of the present invention offers a coercive force of 10 kOe or more even with a small content of Dy, Tb and Ho. SELECTED DRAWING : Figure 1 COPYRIGHT : (C)2017, JPO&INPIT