A sheet guiding apparatus assembled on a shelf includes two guiding members, two adjusting plates, a first spring, two push bars, a second spring and two rotating members. The guiding member has a base board. A front of the base board defines a guiding portion defining a horizontal recess. Each adjusting plate is pivoted to an outside edge of the base board. The push bars are movably received in the horizontal recesses and capable of sliding in the horizontal recesses to drive the corresponding adjusting plates to rotate upward or free the corresponding adjusting plates therefrom. Each rotating member is pivoted to a front of the guiding portion. When the rotating member is turned down, the rotating member touches the push bar and pushes the push bar to move rearward so that further drives the adjusting plate to rotate upward till being perpendicular to the base board.