The generator comprises a stator (10) having a plurality of protruding portions for stator pole (12) on the outer peripheral surface of the stator main unit (11), and a rotor (20) having a plurality of protruding portions for rotor (22) mounted around the stator (10) in a rotatable state. Since the height of the plurality of protruding portions for stator pole (12) decreases along the rotational or reverse rotational direction of the rotor (20), a torque waveform containing odd-order components is generated when the rotor (20) is rotated coaxially around the stator (10). The plurality of protruding portions for stator pole (12) comprises a first protrusion group for stator pole (12A) and a second protrusion group for stator pole (12B), and the first protrusion group for stator pole (12A) and the second protrusion group for stator pole (12B) are formed with the protruding portions for stator pole (12) laid out along the circumferential direction spaced apart from each other. The rotor (10) has a first ring member (21A) and a second ring member (21B) separated from each other in the axial direction at a given distance, a first protrusion group for rotor pole (22A) having half of the plurality of protruding portions for rotor poles (22) aligned along the inner peripheral surface of the first ring member (21A) spaced apart from each other, and a second protrusion group for rotor pole (22B) having half of the plurality of protruding portions for rotor poles (22) aligned along the inner peripheral surface of the second ring member (21B) spaced apart from each other. By placing the first protrusion group for stator pole (12A) and the second protrusion group for stator pole (12B) in the same phase, and shifting the second protrusion group for rotor (22B) from the first protrusion group for rotor (22A) by a mechanical angle allowing their electrical phases to deviate by 180°, odd-order components of the torque waveform can be canceled, and torque ripple can be reduced.