A rotating electric motor includes a rotary shaft capable of rotation, a stator core formed in a cylindrical configuration, a rotor core fixed to the rotary shaft, a magnet set at the rotor core such that a pair of magnetic poles of different magnetism are aligned in the radial direction of the rotor core, a field yoke provided at the perimeter of the stator core, and a winding that can control the magnetic flux density across the rotor core and the stator core by forming a magnetic circuit across the field yoke and the rotor core.