A screw feeding device includes a feeder box, a stopper member, an operating member, and a resilient member. An adjustment slot is formed in the stopper member, and has two closed ends and alternate large-diameter and small-diameter slot portions. An operating protrusion of the operating member has a large-diameter protrusion portion and a small-diameter protrusion portion. The operating protrusion is biased by the resilient member away from the feeder box. The operating member is movable relative to the feeder box between a first position whereat the large-diameter protrusion portion is disposed within a selected one of the large-diameter slot portions, and a second position whereat the small-diameter protrusion portion is disposed in the adjustment slot.