PERMANENT-MAGNET STEPPING MOTOR

A stepping motor uses a low-cost ferrite magnet instead of an expensive rare-earth magnet. The stepping motor has characteristics equivalent or superior to those of a conventional stepping motor. The stepping motor is provided with a rotor 300, a stator yoke 200, and bearings 501 and 502 which rotatably hold the rotor 300 with respect to the stator yoke 200. The rotor 300 has a columnar shape and has plural magnetic poles arranged in the circumferential direction of the outer circumferential surface. The stator yoke 200 has an outer cylindrical portion and an inner circumferential portion which surrounds the rotor 300 and which has plural first pole teeth and plural second pole teeth. The outer diameter "d" of the rotor 300 and the outer diameter "D" of the stator yoke 200 are set so that the ratio of "d/D" is greater than 0.6.