An image forming apparatus includes a fixing unit, a first support portion, and a second support portion. First support portion fits with and positions first supported portion, which is end of fixing unit, in up-down direction and supports first supported portion movably in insertion direction of fixing unit toward attachment position. Second support portion fits with and positions second supported portion, which is another end of fixing unit, in up-down direction and supports second supported portion movably in insertion direction. Height adjustment portion adjusts height position of fixing unit by moving second support portion in up-down direction. The first support portion includes vertical surface facing first supported portion and extending in up-down direction, and vertical surface has projection at an end thereof on foreside of insertion direction, the projection projecting from the vertical surface in first direction of going away from the vertical surface.