The object is to provide an image-forming apparatus which is capable of releasing the heat generated in the apparatus without incorporating a fan. [Means for Solving the Problem]Three ribs 17 are provided to rise on the surface of a recording sheet-receiving tray 16 and to extend in the sheet discharge direction (arrow A direction) The three ribs 17 are arranged in the width direction of the recording paper sheet P held on the sheet-receiving tray 16. The number of the ribs 17 may be two, or four or more, regardless of the three ribs 17 as an example. The sheet-receiving tray 16 has many apertures 16a,16b for connection of the inside of the casing 12 to the outside thereof. The heat generated by a polygon mirror-driving motor 18c, a fixation assembly 36, and so forth is released through many apertures 16a,16b,12a. Therefore, the laser beam printer 10 does not employ a fan for removing the heat from inside of the casing 12.