A permanent-magnet-embedded electric motor comprising: a stator core that includes an annular yoke and a plurality of teeth arranged on an inner side of the yoke at an equal interval in a circumferential direction of the yoke and respectively inwardly projecting from the yoke in a radial direction of the yoke (la); an annular rotor core that is arranged on an inner side of the stator core and includes a plurality of magnet insertion holes formed at an equal interval in a circumferential direction of the annular rotor core; and a plurality of permanent magnets respectively inserted into the plurality of magnet insertion holes, the plurality of permanent magnets being arranged at positions respectively corresponding to sides of an imaginary regular polygon having a same number of corners as number of the magnet insertion holes, each of the permanent magnets with a lateral direction set in a radial direction of the rotor core and with a longitudinal direction set in a direction orthogonal to the radial direction and parallel to the circumferential direction, wherein each of the plurality of teeth includes a base section inwardly projecting from the yoke in the radial direction of the yoke and having a fixed width in a direction orthogonal to the radial direction and parallel to the circumferential direction of the yoke; and a distal end section provided on an inner side of the base section and having a width larger than the fixed width of the base section in the direction orthogonal to the radial direction and parallel to the circumferential direction of the yoke, each of both end sections in the longitudinal direction of each of the plurality of permanent magnets is adjacent to a space section that forms a part of the magnet insertion hole into which the permanent magnet is inserted, and when a width of the base section is represented as S1, a width of the distal end section is represented as S2, a width of the permanent magnet in the longitudinal direction is represented as R1, and a width of the magnet insertion hole along a circumferential direction in which the magnet insertion hole extends is represented as R2, characterized in that relations S1≤R1<S2 and S1≤R2-R1 are satisfied, wherein the permanent-magnet-embedded electric motor further comprises, linearly extending from the end sections of the permanent magnet in the longitudinal direction of the permanent magnet: a pair of space sections, the whole of which is arranged on the same straight line with the permanent magnet. a stator core that includes an annular yoke and a plurality of teeth arranged on an inner side of the yoke at an equal interval in a circumferential direction of the yoke and respectively inwardly projecting from the yoke in a radial direction of the yoke (la); an annular rotor core that is arranged on an inner side of the stator core and includes a plurality of magnet insertion holes formed at an equal interval in a circumferential direction of the annular rotor core; and a plurality of permanent magnets respectively inserted into the plurality of magnet insertion holes, the plurality of permanent magnets being arranged at positions respectively corresponding to sides of an imaginary regular polygon having a same number of corners as number of the magnet insertion holes, each of the permanent magnets with a lateral direction set in a radial direction of the rotor core and with a longitudinal direction set in a direction orthogonal to the radial direction and parallel to the circumferential direction, wherein each of the plurality of teeth includes a base section inwardly projecting from the yoke in the radial direction of the yoke and having a fixed width in a direction orthogonal to the radial direction and parallel to the circumferential direction of the yoke; and a distal end section provided on an inner side of the base section and having a width larger than the fixed width of the base section in the direction orthogonal to the radial direction and parallel to the circumferential direction of the yoke, each of both end sections in the longitudinal direction of each of the plurality of permanent magnets is adjacent to a space section that forms a part of the magnet insertion hole into which the permanent magnet is inserted, and when a width of the base section is represented as S1, a width of the distal end section is represented as S2, a width of the permanent magnet in the longitudinal direction is represented as R1, and a width of the magnet insertion hole along a circumferential direction in which the magnet insertion hole extends is represented as R2, characterized in that relations S1≤R1<S2 and S1≤R2-R1 are satisfied, wherein the permanent-magnet-embedded electric motor further comprises, linearly extending from the end sections of the permanent magnet in the longitudinal direction of the permanent magnet: a pair of space sections, the whole of which is arranged on the same straight line with the permanent magnet.