Abstract: A screw positioning device includes a tubular member coupled to a slidable barrel part of a screw driving gun. The tubular member defines a screw-guiding chamber. Two spring-biased screw-holding units are disposed within the chamber, and include two urging members and two screw-holding members urged by the urging members in such a manner that the screw-holding members come into contact with a screw in the chamber and are pushed by the screw to move radially away from each other and that the screw-holding members are urged by the urging members to abut against the screw.