Abstract: A rotor according to an aspect of the present invention includes columnar rotor core; and permanent magnets arranged side by side along predetermined polar pitch angle in circumferential direction of rotor core when viewed from sight line including axial center of rotor core. The rotor core is formed with openings formed in outer peripheral surface of rotor core and having permanent magnets inserted thereinto; interpole-forming-grooves formed by pair of first and second grooves that each extend in direction of axial center on both circumferential sides of openings, and formed in the same number as the number of magnetic poles; interpole formed between first groove and second groove adjacent to first groove; and rib formed between opening and interpole-forming-groove, in yoke-portion of rotor core. The rib is formed with stress-absorbing-portion made from thin-walled-portion with smallest thickness in yoke-portion in cross-sectional view of cross-section including axial center of rotor.