A rotating electric machine whose output characteristics can be easily and freely adjusted and varied even in operation. The rotating electric machine is received in a housing of an electrically driven two-wheeled vehicle. A rotating shaft is connected to a rotor so as to form an axle. A stator is positioned opposite a rotor. A movable member is connected to a rotating member rotated about the rotating shaft by a regulating motor. The movable member is moved in the axial direction of the rotating shaft by the rotation of the rotating member. This movement causes the rotor to be rotatingly moved in the axial direction o the rotating shaft, changing relative position of the rotor and the stator.