PURPOSE: To facilitate lamination of papers in a stacker, by a method wherein curl is detected at a discharge part for papers by means of the direction of the curl of a paper, and the shape of the curl is changed.

CONSTITUTION: A paper 4, unrolled from a record paper roll 10, is cut by record paper cutters 13 and 14. The cut paper is conveyed through shutters 15 and 16, an upper curl sensor 17, and a lower curl sensor 18 from guides 21 and 22 to a discharge roller 3 and is discharged to a stacker 1. A shifting plate 5 is controlled by means of the upper and the lower curl sensors 17 and 18. In the case of the upper curl, at a point of time when the upper curl sensor 17 is actuated, a solenoid 6 is turned OFF to move out the shifting plate 5 from the stacker 1. In the case of the lower curl, the shifting plate 5 is rotated counterclockwise by attracting the solenoid 6 by means of the sensor 18 to bring the shifting plate into a position shown by a broken line, and an angle at which the forward end of the paper collides is decreased to stack the papers without crumpling the paper into a ball.