An image forming apparatus comprising: a housing accommodating an image forming unit therein and having an opening at one side surface thereof; a cover member pivotally supported to a lower edge portion of the opening and rotated to an outer side of the housing from a closed state, in which the opening is closed, by employing a shaft as a fulcrum, thereby opening the opening; and a long belt-shaped support member having one end portion mounted at the housing and the other end portion mounted at the cover member, and restricting an opening angle of the cover member to a predetermined maximum opening angle, wherein the one end portion and the other end portion of the support member in a longitudinal direction is formed with a mounting portion for connecting each of the end portions to the housing and the cover member respectively, characterized in that the end portion of the center side of the support member in the longitudinal direction is connected to three longitudinal portions that are upright from one side surface of the support member in the thickness direction with respect to the mounting portion, the three longitudinal plate portions connected to each of the mounting portions are disposed on one end portion and the other end portion in the longitudinal direction of the support member with each of the mounting portions, the three longitudinal plate portions are formed to be spaced apart from each other to face each other in the direction perpendicular to the longitudinal direction of the support member, and the three longitudinal plate portions are formed in a right-angled triangle shape so that its height in a thickness direction is gradually reduced toward a center side from an end side of the support member in the longitudinal direction, the adjacent three longitudinal plate portions are connected each other by two transversal rib portions each vertically intersecting with each of the longitudinal plate portions and arranged spaced apart from each other in the longitudinal direction of the support member. a housing accommodating an image forming unit therein and having an opening at one side surface thereof; a cover member pivotally supported to a lower edge portion of the opening and rotated to an outer side of the housing from a closed state, in which the opening is closed, by employing a shaft as a fulcrum, thereby opening the opening; and a long belt-shaped support member having one end portion mounted at the housing and the other end portion mounted at the cover member, and restricting an opening angle of the cover member to a predetermined maximum opening angle, wherein the one end portion and the other end portion of the support member in a longitudinal direction is formed with a mounting portion for connecting each of the end portions to the housing and the cover member respectively, characterized in that the end portion of the center side of the support member in the longitudinal direction is connected to three longitudinal portions that are upright from one side surface of the support member in the thickness direction with respect to the mounting portion, the three longitudinal plate portions connected to each of the mounting portions are disposed on one end portion and the other end portion in the longitudinal direction of the support member with each of the mounting portions, the three longitudinal plate portions are formed to be spaced apart from each other to face each other in the direction perpendicular to the longitudinal direction of the support member, and the three longitudinal plate portions are formed in a right-angled triangle shape so that its height in a thickness direction is gradually reduced toward a center side from an end side of the support member in the longitudinal direction, the adjacent three longitudinal plate portions are connected each other by two transversal rib portions each vertically intersecting with each of the longitudinal plate portions and arranged spaced apart from each other in the longitudinal direction of the support member.