An IPM rotor, comprising: a rotor core which includes a plurality of core sheets, and has an accommodation hole; and a magnet (4, 4A, 4B) accommodated in the accommodation hole, wherein the plurality of core sheets include a plurality of first core sheets (20, 60) and a plurality of second core sheets (30, 70), wherein the first core sheet (20, 60) has a first sheet hole (20a, 60a) forming a part of the accommodation hole, wherein the second core sheet (30, 70) has a second sheet hole (30a, 70a) forming a part of the accommodation hole, wherein the first sheet hole (20a, 60a) has an edge portion having a flat spring portion (20e, 60d, 60e) which is bent by the magnet (4, 4A, 4B) through insertion of the magnet (4, 4A, 4B) into the accommodation hole, wherein the second sheet hole (30a, 70a) has an edge portion having a concave portion (30e, 70d, 70e) which accommodates the flat spring portion (20e, 60d, 60e) bent by the magnet (4, 4A, 4B), wherein a pair of recesses (20f, 60f) forming a clearance with respect to the magnet (4, 4A, 4B) are formed at both side portions of the flat spring portion (20e, 60d, 60e) of the edge portion of the first sheet hole (20a, 60a), characterized in that a length of the flat spring portion (20e, 60d, 60e) is two to three times larger than a thickness of the first core sheet (20, 60), a width of the flat spring portion (20e, 60d, 60e) is equal to or smaller than 30% of a length of the magnet (4, 4A, 4B) in a width direction of the flat spring portion (20e, 60d, 60e), and a bottom surface of the recess (20f, 60f) and a bottom surface of the concave portion (30e, 70d, 70e) are located at the same position in a radial direction of the rotor core. a rotor core which includes a plurality of core sheets, and has an accommodation hole; and a magnet (4, 4A, 4B) accommodated in the accommodation hole, wherein the plurality of core sheets include a plurality of first core sheets (20, 60) and a plurality of second core sheets (30, 70), wherein the first core sheet (20, 60) has a first sheet hole (20a, 60a) forming a part of the accommodation hole, wherein the second core sheet (30, 70) has a second sheet hole (30a, 70a) forming a part of the accommodation hole, wherein the first sheet hole (20a, 60a) has an edge portion having a flat spring portion (20e, 60d, 60e) which is bent by the magnet (4, 4A, 4B) through insertion of the magnet (4, 4A, 4B) into the accommodation hole, wherein the second sheet hole (30a, 70a) has an edge portion having a concave portion (30e, 70d, 70e) which accommodates the flat spring portion (20e, 60d, 60e) bent by the magnet (4, 4A, 4B), wherein a pair of recesses (20f, 60f) forming a clearance with respect to the magnet (4, 4A, 4B) are formed at both side portions of the flat spring portion (20e, 60d, 60e) of the edge portion of the first sheet hole (20a, 60a), characterized in that a length of the flat spring portion (20e, 60d, 60e) is two to three times larger than a thickness of the first core sheet (20, 60), a width of the flat spring portion (20e, 60d, 60e) is equal to or smaller than 30% of a length of the magnet (4, 4A, 4B) in a width direction of the flat spring portion (20e, 60d, 60e), and a bottom surface of the recess (20f, 60f) and a bottom surface of the concave portion (30e, 70d, 70e) are located at the same position in a radial direction of the rotor core.