A brushless DC motor wherein a rotor has a motor shaft, a rotor yoke mounted on the motor shaft, and a ring-shaped magnet magnetized so as to have a plurality of magnet poles in the circumferential direction thereof, and held by the rotor yoke. A stator has first and second stator yokes each having main magnetic poles extending in the radial direction from the center thereof, magnetic pole pieces extending in the vertical direction from tip ends of the main magnetic poles along an inner peripheral surface of the ring-shaped magnet, a center yoke surrounding the motor shaft for connecting magnetically said first and second stator yokes, a winding assembly having an annular winding, and a printed wiring board, on which the annular winding, a electromagnetic conversion element and a driving circuit are mounted.