As shown in Table 1, the amorphous soft magnetic material of Reference Example 1 had tensile strength larger than those of the nanocrystal soft magnetic material of Reference Example 2 and the magnetic steel sheet of Reference Example 3. The amorphous soft magnetic material of Reference Example 1 had saturated magnetization smaller than those of the nanocrystal soft magnetic material of Reference Example 2 and the magnetic steel sheet of Reference Example 3. These results show that a rotor core including a part of the bridges made of an amorphous soft magnetic material will be stronger than a rotor core made of a nanocrystal soft magnetic material as stated above. A rotor core of an IPM motor is designed to flow less magnetic flux from a magnet through the bridges. The bridges made of an amorphous soft magnetic material of the rotor core allow the magnetic flux from a magnet to flow to the stator through the other parts efficiently, and so the output characteristics of the motor improve.