<p>An image forming apparatus including an image forming section (2) ; an upper unit (30) located over the image forming section with a space therebetween and slidable in a direction of from the front side to the rear side of the apparatus and the opposite direction; a sheet discharger (25) for discharging a sheet (S) bearing an image in the first or opposite direction; a sheet stacker (40) receiving the sheet from the sheet discharger; a support (50) arranged outside of both side ends of the sheet stacker in the sheet discharging direction and slidably supporting the upper unit; and a release preventing member (53; 54) for preventing releasing of the upper unit from the support, or a covering member (90) movable from a first position to a second position in conjunction with sliding of the upper unit and covering an opening (59) formed at an end portion of the support when acquiring the first position.</p>
