Electric rotary machine

The invention provides an electric rotary machine for decreasing the iron loss caused by a flux flow on a rotating axis direction under the state of a mechanical weakening magnetic field when rotating speedily. The electric rotary machine comprises a stator (1) with an armature coil and a rotor, wherein the rotor is incorporated rotatably inside the stator keeping an air gap (7), is divided into at least two parts of a first rotor (4) and a second rotor (5) in a direction of a rotating shaft thereof, and all parts have field magnets with different polarities disposed alternatively in a rotating direction of the rotor. A magnetic flux control mechanism controls effective magnetic fluxes by varying positions of the field magnets of the second rotor (5) relatively with respect to that of the first rotor (4) in at least the rotating direction of the rotor. A magneto-resistive layer (9) is interposed in the path of the effective magnetic fluxes in the stator.