Abstract: An improved 10-pole 9-slot brushless DC motor used as a spindle motor used in devices, such as a computer hard disk driver or a laser scanner, is provided which reduces cogging torque and improves driving torque. The motor includes a field magnet having an annular permanent magnet which is formed of 10 magnetic poles attached to each other in a radial orientation, for generating a flux field and an armature formed by winding an armature core formed of nine slots and nine salient-poles with windings connected in three phases. Also, the field magnet of the motor is rotated by the rotating magnetic field generated by the armature windings. Since the motor has a short cycle and low cogging torque, the motor is very stable. Also, torque ripple is low and the torque characteristics as a whole are improved, thus achieving high efficiency.