An electric rotating machine comprises: a stator in which a coil is wound on a plurality of teeth in concentrated winding, and the coil is connected to a three-phase power supply; and a rotor disposed in opposition to the teeth of the stator; wherein a ratio between the number of poles and the number of slots of the stator is 1:3. There is no higher harmonics of magnetomotive force in low order close to fundamental wave, thus enabling efficient operation of the electric rotating machine. Furthermore, owing to the stator of concentrated winding, it is possible to provide an electric rotating machine of high productivity with small coil end, high mass production, and high space factor.