Abstract: A rotor structure of a permanent magnet (PM) stepping motor includes a permanent magnet and two multiple yokes, both of which are stacked together to form a rotor structure with hamburger-like multipolar yoke stacks. The top and bottom layers of each multipolar yoke stacks can be multipolar yokes with a gear shape, forming an NS stack structure with a multipolar magnetic field. This structure has the advantage of a minimized magnetic pole span and a high torque, which cannot be achieved in conventional stepping motors.