PURPOSE: To align paper loaded on a tray well without shifting paper even if the paper has a curled part in it, and discharge the paper smoothly.

CONSTITUTION: A pair of detection sensors 14a, 14b are disposed at a prescribed distance in the orthogonal direction to the discharging direction of paper discharged from an image forming device to detect the displacement of the front surface (loaded surface) of the paper 3 loaded on a tray 1. A tray inclining mechanism which inclines the tray in the orthogonal direction to the discharging direction of the paper is provided. When it is detected that one surface in the side direction of the paper is curled and standing, one of a pair of right and left lifting motors 5a, 5b which constitutes the tray inclining mechanism is driven to incline the tray 1 and keep the loaded surface horizontal.