Abstract: A step motor includes a spindle, a magnet unit mounted around the spindle, and a stator assembly sleeved over the magnet unit. The stator assembly includes at least one coil-and-yoke unit having a coil support, a coil wound around the coil support, an outer tube sleeved over the coil, and a pair of magnetic yokes mounted in the coil support. A fixing plate and a cover unit are mounted to opposite ends of the stator assembly. The coil support includes a surrounding wall, and a positioning tab protruding from the surrounding wall. Notches are formed in the outer tube, and the positioning tab engages one of the notches. Each of the magnetic yokes includes an orientation fixing member that engages one of the notches, and a plurality of excitation fingers inserted into the coil support and circumferentially uniformly distributed.