To provide a driving mechanism for surely rotating a movable section up to a regulated rotation range.

The driving mechanism is provided with: a movable paper guide 800 which is rotatable around a rotary shaft 810; a driven section 830 which is fixed on the rotary shaft 810 and is rotatable together with the rotary shaft 810; fixed side regulation sections (850, 852) for regulating the rotation range of the movable paper guide 800; a coil spring 820 which rotates together with the driven section 830 and holds the movable paper guide 800 rotatably around the rotary shaft 810 by a predetermined amount with respect to the driven section 830; and a rotational driving section 860 for rotationally driving the driven section 830 by a rotational amount larger than the rotation range regulated by the fixed side regulation sections (850, 852) by the predetermined amounts or less.