A sheet pick-up device includes a sheet pick-up arm, a driving shaft and a collar. The sheet pick-up arm has a sleeve at the outside surface thereof. The driving shaft is penetrated through the sheet pick-up arm and the sleeve. The collar is sheathed around the driving shaft and includes at least one flexible vane in contact with the inner surface of the sleeve. The height of the flexible vane relative to the outer surface of the collar is greater than the radial distance between the outer surface of the collar and the inner surface of the sleeve.