There is provided a soft magnetic alloy comprising a composition expressed by a formula of (Fe(1-α)Aα)(1-m-x-y)MmXxYy, in which M represents at least one selected from the group consisting of Zr and Hf, X represents at least one selected from the group consisting of Ni, Mn, Cu, Co, Al, and Ge, Y represents at least one selected from the group consisting of B, P, and Si, A represents at least one selected from the group consisting of Ti, V, Cr, Zn, Mg, Sn, Bi, O, N, S, and a rare earth element, m, x, y, and α satisfy relationships of 0.070≤m≤0.120, 0.001≤x≤0.030, 0≤y≤0.010, and 0≤α≤0.100, and the alloy contains Fe-based nanocrystals having an average crystal grain size of 30 nm or less.