A rotor core according to an embodiment has a plurality of magnet openings and cavity portions. The magnet openings are in juxtaposition with each other in a circumferential direction. Permanent magnets are inserted in the magnet openings. The cavity portions are each formed relative to an area sandwiched between two magnet openings, out of the magnet openings, in which the permanent magnets that are mutually adjacent and that have magnetic pole directions relative to a radial direction opposite to each other are inserted.