A driving device includes a motor, a rotatable shaft rotated by the motor, a driven member, a magnetic material spring, and a power source. The driven member sleeves on an end of the rotatable shaft, and includes an end surface with at least one latching groove defined thereon. The magnetic material spring sleeves the rotatable shaft, and includes a first end fixed to the rotatable shaft and an opposite second end capable of inserting into the latching groove of the driven member. The power source includes two electrodes. The motor and the spring are electrically connected in series between the two electrodes of the power source.