Abstract: A screw feed apparatus for use with a power screwdriving tool comprises a casing relatively slidably mounted on an adapter detachable to the tool, a pair of brackets mounted to the forward end of the casing, a pair of feed sprockets disposed within the brackets and engageable with a magazine belt which carries a series of self-drilling screws, a ratchet wheel supported by the brackets so as to be co-rotatable with the feed sprockets, a slide member supported on the casing so as to move toward the ratchet wheel in response to forward movement of the adapter and move away from the ratchet wheel in response to rearward movement of the adapter, and a claw member operatively supported by the slide member so as to force the ratchet wheel to rotate intermittently by a regular pitch as the slide member moves away from the ratchet wheel.