PURPOSE:To uncurl a paper by arranging projections near the central portion of a bottom member along paper discharge direction and providing a paper discharge tray. CONSTITUTION:When a driving paper discharge roller 16a rotates, a recording paper formed with an image is carried while being held between the drive side paper discharge roller 16a and a driven side paper discharge roller 16b, then discharged onto a paper discharge tray 10. The paper is discharged while being curled differently according to the thickness, material and the direction of fibers. Since the discharging paper is bent at a portion contacting with a projection 13, the paper advances while being uncurled with lateral end potions thereof being guided through sideboards 12, 12. Tip portion 17a of the paper 17 is blocked from advancing by a front edge sideboard 18 of the paper discharge tray 10. Consequently, many printed papers are stacked regularly onto the paper discharge tray 10.