An image forming apparatus including a hinge assembly to mutually hinge-connect a main body and a cover unit of the image forming apparatus and the hinge assembly is provided. The image forming apparatus includes a main body, a cover unit configured to be disposed on an upper side of the main body to press a manuscript, and at least one hinge assembly configured to connect the cover unit to the main body, wherein the hinge assembly includes a first body detachably mounted on the main body, a second body of which a part is fastened to the cover unit and another part is hinge-connected with the first body, a pressing unit accommodated in the first body to press the second body upward, and a pressing force adjuster configured to adjust a hinge force between the first body and the second body.