A magnetic core and the like having a stable soft magnetic property, including a plurality of soft magnetic layers which are laminated, wherein a crack is formed in the soft magnetic layers. The soft magnetic layers include Fe as a principal component. The soft magnetic layers include a composition formula (Fe(1−(α+β))X1αX2β)(1−(a+b+c+d+e+f))MaBbPcSidCeSf, wherein: X1 is one or more selected from the group consisting of Co and Ni, X2 is one or more selected from the group consisting of Al, Mn, Ag, Zn, Sn, As, Sb, Cu, Cr, Bi, N, and O and rare-earth elements, M is one or more selected from the group consisting of Nb, Hf, Zr, Ta, Mo, V, and W; and a to f and α and β are in predetermined ranges. A structure including a nanoheterostructure or an Fe-group nanocrystal is observed in the soft magnetic layers.