The present invention provides an electric rotating machine capable of providing a high quality and efficient machine operation with reduced oscillation and noise by lowering torque ripple. The electric rotating machine includes a stator having a plurality of teeth facing a rotor, and a plurality of slots providing spaces for winding coils around the teeth. The rotor has a pair of permanent magnets embedded therein and located in a “V” shape configuration so as to let magnetic force act on the teeth such that the rotor within said stator is driven to revolve by reluctance torque and magnet torque. An outer diameter ratio Δ of an outer diameter Dr of the rotor to an outer diameter Ds of the stator falls in a range from 0.61 to 0.645.