An image reading device includes: a housing, a document loading surface, a reading unit, a first through hole, a second through hole, an insertion member, and a first member. The first through hole is provided in a manner such as to be pierced through the housing. The second through hole is provided oppositely to the first through hole in a manner such as to be pierced through the reading unit located at a predefined place. When being inserted in the first through hole and the second through hole, the insertion member stops movement of the reading unit in a horizontal direction and fixes the reading unit in the housing. The first member closes the first through hole and has a shape deforming in accordance with the insertion of the insertion member in the first through hole and the second through hole.

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.