The present invention relates to a soft magnetic alloy including, in terms of at %: 7.0%Si15.0%; 7.0%B10.0%; 0.5%Cu2.0%; 0.03%C0.30%; 0.005%S0.050%; and 3.0%<X5.0%, X being at least one element selected from the group consisting of Ti, Nb, V, Zr, Hf, Ta, and W, with the balance being Fe and unavoidable impurities, or being Fe, at least one selected from the group consisting of Ni with which a part of Fe is substituted and Co with which a part of Fe is substituted, and unavoidable impurities.

A high-strength R-T-B rare earth permanent magnet having an amorphous grain boundary phase includes: 29.0 wt. %-34.0 wt. % of large-atomic-radius elements with the atomic radius r satisfying r0.16 nm, said large-atomic-radius elements comprising 0.1 wt. %-0.8 wt. % of Mf, and Mf being any one or two of Zr and Mg; 1.05 wt. %-1.65 wt. % of small-atomic-radius elements with r0.12 nm, said small-atomic-radius elements comprising 0.8 wt. %-1.1 wt. % of boron element, and the total content C1 of the small-atomic-radius elements satisfying 0.25 wt. %[C1][B]0.55 wt. %; and the balance being medium-atomic-radius elements with 0.12 nm<r<0.16 nm and impurities, said medium-atomic-radius elements at least comprising 60.0 wt. % of TM, the TM being at least one of Fe and Co, and the content of other medium-atomic-radius elements except said TM being 0.2 wt. %. In the present invention, the proportion of the amorphous grain boundary phase in the grain boundary phase of the magnet is increased to 20 vol. % or more, thereby improving the capability of resisting crack propagation of the grain boundary phase of the magnet, and manufacturing a high-strength R-T-B rare earth permanent magnet.