A dynamo-electric machine comprising: a stator having salient poles each wound with a coil; a rotor rotatably disposed on one of an outer circumference and an inner circumference of said stator, said rotor having permanent magnets fixed thereto along a circumferential direction thereof; and two pole-pair groups (16a, 16b) disposed point-symmetrically with respect to a center of said stator, with space for allowing an additional arrangement of salient poles being defined between said two pole-pair groups, wherein each one of said two pole-pair groups (16a, 16b) includes pole pairs (15Ua, 15 Va, 15 Wa; 15 Ub, 15 Vb, 15 Wb) each composed of circumferentially adjacent ones of said salient poles that are of the same phase, with each of said circumferentially adjacent ones of said salient poles facing one of said permanent magnets that is different in polarity relative to the one of said permanent magnets that is faced by another of said circumferentially adjacent ones of said salient poles, with said circumferentially adjacent ones of said salient poles that are of the same phase facing respective ones of said permanent magnets at the same electric angle, and with the number of pole-pairs being equal in number to the number of phases, wherein an angle θ1 between said circumferentially adjacent ones of said salient poles that are of the same phase is equal to 360°/N, and an angle θ2 between circumferentially adjacent ones of said salient poles that are not of the same phase is equal to θ1+(θ1/P), with P being the number of phases and N being the number of poles of said permanent magnets, and wherein an angle X of said each one of said two pole-pair groups (16a, 16b) is equal to an integral multiple of an arrangement interval of said permanent magnets. a stator having salient poles each wound with a coil; a rotor rotatably disposed on one of an outer circumference and an inner circumference of said stator, said rotor having permanent magnets fixed thereto along a circumferential direction thereof; and two pole-pair groups (16a, 16b) disposed point-symmetrically with respect to a center of said stator, with space for allowing an additional arrangement of salient poles being defined between said two pole-pair groups, wherein each one of said two pole-pair groups (16a, 16b) includes pole pairs (15Ua, 15 Va, 15 Wa; 15 Ub, 15 Vb, 15 Wb) each composed of circumferentially adjacent ones of said salient poles that are of the same phase, with each of said circumferentially adjacent ones of said salient poles facing one of said permanent magnets that is different in polarity relative to the one of said permanent magnets that is faced by another of said circumferentially adjacent ones of said salient poles, with said circumferentially adjacent ones of said salient poles that are of the same phase facing respective ones of said permanent magnets at the same electric angle, and with the number of pole-pairs being equal in number to the number of phases, wherein an angle θ1 between said circumferentially adjacent ones of said salient poles that are of the same phase is equal to 360°/N, and an angle θ2 between circumferentially adjacent ones of said salient poles that are not of the same phase is equal to θ1+(θ1/P), with P being the number of phases and N being the number of poles of said permanent magnets, and wherein an angle X of said each one of said two pole-pair groups (16a, 16b) is equal to an integral multiple of an arrangement interval of said permanent magnets.