To provide an image forming apparatus having a shield cover on an ejected paper tray in order to form a water vapor retaining space, in which dew condensation caused by the increase of the quantity of water vapor flowing out into the water vapor retaining space during image formation, is prevented, and dew condensation caused by a temperature drop (dew condensation due to a dew point drop) in the wet water vapor retaining space after the image formation is also prevented.

A heater is provided in a cover member for covering the front surface of an ejected paper tray and a dehumidifying agent is provided in a stacked tray also.