The rotor core 30 of the present embodiment has inner bridges 36 and outer bridges 38. The inner bridges 36 extend between adjacent through-holes 32A, 32B. The outer bridges 38 are located between the through-hole 32A (32B) close to the outer circumference 39 of the rotor core 30 and the outer circumference 39 of the rotor core 30.

In the rotor core 30, both of the bridges including the inner bridges 36 and the outer bridges 38 are made of an amorphous soft magnetic material, and parts other than the bridges are made of a nanocrystal soft magnetic material.

Examples of the amorphous soft magnetic material and the nanocrystal soft magnetic material include, but are not limited to, a material including at least one type of magnetic metal selected from the group consisting of Fe, Co and Ni and at least one type of non-magnetic metal selected from the group consisting of B, C, P, Al, Si, Ti, V, Cr, Mn, Cu, Y, Zr, Nb, Mo, Hf, Ta and W.

Typical materials of the amorphous soft magnetic material and the nanocrystal soft magnetic material include, but are not limited to, FeCo alloys (e.g., FeCo and FeCoV), FeNi alloys (e.g., FeNi, FeNiMo, FeNiCr, and FeNiSi), FeAl alloys or FeSi alloys (e.g., FeAl, FeAlSi, FeAlSiCr, FeAlSiTiRu, and FeAlO), FeTa alloys (e.g., FeTa, FeTaC, and FeTaN) and FeZr alloys (e.g., FeZrN). In some embodiments, the Fe alloy includes 80 at % or more of Fe.