An image forming apparatus includes a shielding member protruding from a top surface of an upper frame and forming a chamber portion having a predetermined area together with an upper cover of the main body covering the shielding member so as to include a plurality of heat dissipating holes perforated in the upper frame at predetermined intervals along a lengthwise direction, and a pump installed at one side of the chamber portion and blowing air into the chamber portion to form a laminar flow to prevent heat generated by a fusing roller from heating an upper cover of the image forming apparatus.