The plurality of flux barriers 25, 26, 27, and 28 are in fluid communication with the plurality of magnet insertion holes 23 formed in the rotor 20. For example, the flux barriers 25, 26, 27, and 28 may be formed to protrude laterally from the magnet insertion holes 23 along the outer circumferential surface of the rotor 20. Because the plurality of flux barriers 25, 26, 27, and 28 all have the same structure, the two flux barriers 25, 26, 27, and 28 provided at opposite ends of the one magnet insertion hole 23 will be described in detail with reference to FIG. 3.

When the permanent magnet 30 is inserted into the magnet insertion hole 23, the ends 31 and 32 of the permanent magnet 30 are positioned in the flux barriers 25, 26, 27, and 28, respectively. Therefore, left flux barriers 25 and 27 and right flux barriers 26 and 28 may be positioned on the left and right sides of the ends 31 and 32 of the permanent magnet 30, respectively. In other words, the left flux bather 25 and the right flux barrier 26 are provided on the left and right sides of the first end 31 of the permanent magnet 30. The left flux barrier 27 and the right flux barrier 28 are also provided on the left and right sides of the second end 32 of the permanent magnet 30. The left flux barriers 25 and 27 and the right flux barriers 26 and 28 all are in fluid communication with the magnet insertion hole 23.