A rotor comprising: an annular rotor core in which a plurality of magnet insertion holes are formed along a circumferential direction; and a plurality of permanent magnets inserted into the magnet insertion holes, respectively, wherein the rotor core is configured by alternately stacking, in an axial direction of the rotor core, each of two first core blocks and one second core block, the first core blocks having no slit on an outer side of each of the magnet insertion holes in a radial direction of the rotor core, the second core block having only one pair of slits (15a, 15b) on the outer side of each of the magnet insertion holes in the radial direction of the rotor core, one slit of the pair of slits (15a, 15b) on the outer side of each of the magnet insertion holes in the radial direction and one end of the corresponding one of the permanent magnets in the circumferential direction are arrayed in the radial direction of the rotor core, and another slit of the pair of slits (15a, 15b) on the outer side of each of the magnet insertion holes in the radial direction and another end of the corresponding one of the permanent magnets in the circumferential direction are arrayed in the radial direction of the rotor core, a ratio of a total length of the first core blocks in the axial direction to a length of the rotor core in the axial direction is 0.35 or higher and 0.45 or lower, the shape of the slits (15a, 15b) does not change along the axial direction, and the second core block is disposed at a center in the axial direction and the first core blocks are disposed so as to sandwich the second core block from both sides in the axial direction. an annular rotor core in which a plurality of magnet insertion holes are formed along a circumferential direction; and a plurality of permanent magnets inserted into the magnet insertion holes, respectively, wherein the rotor core is configured by alternately stacking, in an axial direction of the rotor core, each of two first core blocks and one second core block, the first core blocks having no slit on an outer side of each of the magnet insertion holes in a radial direction of the rotor core, the second core block having only one pair of slits (15a, 15b) on the outer side of each of the magnet insertion holes in the radial direction of the rotor core, one slit of the pair of slits (15a, 15b) on the outer side of each of the magnet insertion holes in the radial direction and one end of the corresponding one of the permanent magnets in the circumferential direction are arrayed in the radial direction of the rotor core, and another slit of the pair of slits (15a, 15b) on the outer side of each of the magnet insertion holes in the radial direction and another end of the corresponding one of the permanent magnets in the circumferential direction are arrayed in the radial direction of the rotor core, a ratio of a total length of the first core blocks in the axial direction to a length of the rotor core in the axial direction is 0.35 or higher and 0.45 or lower, the shape of the slits (15a, 15b) does not change along the axial direction, and the second core block is disposed at a center in the axial direction and the first core blocks are disposed so as to sandwich the second core block from both sides in the axial direction.