Abstract: A scanner has a hollow base, a bracket securely received in the hollow base and having a paper-pressing bar mounted onto the bracket, a top seat securely provided to one side of the hollow base and a top cover mounted on top of the top seat. The top cover has a pressing plate extending into an interior of the top seat and a pair of pressers each extending to engage with and abut the paper-pressing bar. The paper-pressing bar has a driven gear mounted on one distal end thereof so as to correspond to a driving gear of the bracket and a rubber sleeve mounted on the paper-pressing bar to increase a friction. The paper-pressing bar is releasably mounted on a pair of cutouts in the bracket so that the paper-pressing bar is able to move vertically relative to the bracket.