An RE-containing alloy, which is represented by a compositional formula of RrTtAa (wherein R represents at least one rare earth element selected from among La, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Tm, Yb, Gd, and Lu; T collectively represents transition metal elements containing at least Fe atoms, a portion of the Fe atoms being optionally substituted by at least one species selected from among Co, Ni, Mn, Pt, and Pd; A represents at least one element selected from among Al, As, Si, Ga, Ge, Mn, Sn, and Sb; and r, t, and a have the following relationships: 5.0 at. %≦r≦6.8 at. %, 73.8 at. %≦t≦88.7 at. %, and 4.6 at. %≦a≦19.4 at. %) and having an alloy microstructure containing an NaZn13-type crystal structure in an amount of at least 85 mass % and α-Fe in an amount of 5-15 mass % inclusive.